diff --git a/core/org.eclipse.cdt.ui/plugin.properties b/core/org.eclipse.cdt.ui/plugin.properties
index 26d35f88f4e..f7561adcaba 100644
--- a/core/org.eclipse.cdt.ui/plugin.properties
+++ b/core/org.eclipse.cdt.ui/plugin.properties
@@ -179,6 +179,7 @@ ColoringPreferencePage.name=Syntax Coloring
 FoldingPreferencePage.name=Folding
 HoverPreferencePage.name=Hovers
 markOccurrencesPreferencePage.name= Mark Occurrences
+ScalabilityPreferencePage.name=Scalability
 
 DefaultBinaryFileEditor.name = Default Binary File Editor
 AsmEditor.name = Assembly Editor
diff --git a/core/org.eclipse.cdt.ui/plugin.xml b/core/org.eclipse.cdt.ui/plugin.xml
index 85e08d57f55..cd41b1a9982 100644
--- a/core/org.eclipse.cdt.ui/plugin.xml
+++ b/core/org.eclipse.cdt.ui/plugin.xml
@@ -761,6 +761,11 @@
             category="org.eclipse.cdt.ui.preferences.CEditorPreferencePage"
             class="org.eclipse.cdt.internal.ui.preferences.MarkOccurrencesPreferencePage"
             id="org.eclipse.cdt.ui.preferences.MarkOccurrencesPreferencePage"/>
+      <page
+            name="%ScalabilityPreferencePage.name"
+            category="org.eclipse.cdt.ui.preferences.CPluginPreferencePage"
+            class="org.eclipse.cdt.internal.ui.preferences.ScalabilityPreferencePage"
+            id="org.eclipse.cdt.ui.preferneces.CScalabilityPreferernces"/>
       <!--page
             name="%WorkInProgress.name"
             category="org.eclipse.cdt.ui.preferences.CPluginPreferencePage"
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/ICHelpContextIds.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/ICHelpContextIds.java
index 0eea6b39633..27e3ad57d23 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/ICHelpContextIds.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/ICHelpContextIds.java
@@ -171,4 +171,6 @@ public interface ICHelpContextIds {
 
 	public static final String PATHENTRY_VARIABLES_PREFERENCE_PAGE= PREFIX + "pathentry_variables_preference_page_context"; //$NON-NLS-1$
 
+	public static final String SCALABILITY_PREFERENCE_PAGE = PREFIX + "scalability_preference_page_context"; //$NON-NLS-1$
+
 }
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditor.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditor.java
index 3189aea262e..c1b31443a1a 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditor.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditor.java
@@ -43,6 +43,9 @@ import org.eclipse.jface.action.IMenuManager;
 import org.eclipse.jface.action.IStatusLineManager;
 import org.eclipse.jface.action.MenuManager;
 import org.eclipse.jface.action.Separator;
+import org.eclipse.jface.dialogs.IDialogConstants;
+import org.eclipse.jface.dialogs.MessageDialog;
+import org.eclipse.jface.dialogs.MessageDialogWithToggle;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.BadPositionCategoryException;
@@ -92,6 +95,7 @@ import org.eclipse.jface.text.source.IOverviewRuler;
 import org.eclipse.jface.text.source.ISourceViewer;
 import org.eclipse.jface.text.source.ISourceViewerExtension2;
 import org.eclipse.jface.text.source.IVerticalRuler;
+import org.eclipse.jface.text.source.SourceViewer;
 import org.eclipse.jface.text.source.SourceViewerConfiguration;
 import org.eclipse.jface.text.source.projection.ProjectionAnnotationModel;
 import org.eclipse.jface.text.source.projection.ProjectionSupport;
@@ -116,6 +120,7 @@ import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.ui.IActionBars;
 import org.eclipse.ui.IEditorActionBarContributor;
@@ -203,6 +208,7 @@ import org.eclipse.cdt.internal.ui.search.actions.SelectionSearchGroup;
 import org.eclipse.cdt.internal.ui.text.CHeuristicScanner;
 import org.eclipse.cdt.internal.ui.text.CPairMatcher;
 import org.eclipse.cdt.internal.ui.text.CSourceViewerConfiguration;
+import org.eclipse.cdt.internal.ui.text.CSourceViewerScalableConfiguration;
 import org.eclipse.cdt.internal.ui.text.CTextTools;
 import org.eclipse.cdt.internal.ui.text.CWordFinder;
 import org.eclipse.cdt.internal.ui.text.CWordIterator;
@@ -1232,6 +1238,12 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
 	 * @since 4.0
 	 */
 	private TextViewerDragAdapter fTextViewerDragAdapter;
+	
+	/**
+	 * True if editor is opening a large file.
+	 * @since 5.0
+	 */
+	private boolean fEnableScalablilityMode = false;
 
 	private static final Set<String> angularIntroducers = new HashSet<String>();
 	static {
@@ -1325,6 +1337,33 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
 		} else {
 			fBracketMatcher.configure(null);
 		}
+	
+		int lines = getDocumentProvider().getDocument(input).getNumberOfLines();
+		if (lines > getPreferenceStore().getInt(PreferenceConstants.SCALABILITY_NUMBER_OF_LINES)) {
+			//Detecting if scalability mode should be turned on
+			fEnableScalablilityMode = true;
+			
+			//Alert users that scalability mode should be turned on
+			if (getPreferenceStore().getBoolean(PreferenceConstants.SCALABILITY_ALERT)) {
+				MessageDialogWithToggle dialog = new MessageDialogWithToggle(
+						Display.getCurrent().getActiveShell(), 
+						CEditorMessages.getString("Scalability.info"),  //$NON-NLS-1$
+						null, 
+						CEditorMessages.getString("Scalability.message"),  //$NON-NLS-1$
+						MessageDialog.INFORMATION, 
+						new String[] {IDialogConstants.OK_LABEL}, 0, 
+						CEditorMessages.getString("Scalability.reappear"),  //$NON-NLS-1$
+						false) {
+					@Override
+					protected void buttonPressed(int buttonId) {	
+						PreferenceConstants.getPreferenceStore().setValue(PreferenceConstants.SCALABILITY_ALERT, !getToggleState());
+						super.buttonPressed(buttonId);
+					}
+				};				
+				dialog.setBlockOnOpen(false);
+				dialog.open();				
+			}
+		}
 	}
 
 	/*
@@ -1337,7 +1376,7 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
 		SourceViewerConfiguration sourceViewerConfiguration= getSourceViewerConfiguration();
 		if (!(sourceViewerConfiguration instanceof CSourceViewerConfiguration)) {
 			CTextTools textTools= CUIPlugin.getDefault().getTextTools();
-			setSourceViewerConfiguration(new CSourceViewerConfiguration(textTools.getColorManager(), store, this, ICPartitions.C_PARTITIONING));
+			setSourceViewerConfiguration(new CSourceViewerScalableConfiguration(textTools.getColorManager(), store, this, ICPartitions.C_PARTITIONING));
 		}
 
 		if (getSourceViewer() instanceof CSourceViewer)
@@ -1377,6 +1416,8 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
      * @return Outline page.
 	 */
 	public CContentOutlinePage getOutlinePage() {
+		if (isEnableScalablilityMode() && getPreferenceStore().getBoolean(PreferenceConstants.SCALABILITY_RECONCILER))
+    		return null;
 		if (fOutlinePage == null) {
 			fOutlinePage = new CContentOutlinePage(this);
 			fOutlinePage.addSelectionChangedListener(this);
@@ -1557,6 +1598,17 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
 				if (c instanceof ContentAssistant) {
 					ContentAssistPreference.changeConfiguration((ContentAssistant) c, getPreferenceStore(), event);
 				}
+				
+				//For Scalability
+				if (PreferenceConstants.SCALABILITY_RECONCILER.equals(property)) {
+						((SourceViewer)getSourceViewer()).unconfigure();
+						getSourceViewer().configure(getSourceViewerConfiguration());
+				}
+				
+				if (PreferenceConstants.SCALABILITY_SYNTAX_COLOR.equals(property)) {
+					((SourceViewer)getSourceViewer()).unconfigure();
+					getSourceViewer().configure(getSourceViewerConfiguration());
+				}
 			}
 		} finally {
 			super.handlePreferenceStoreChanged(event);
@@ -3251,4 +3303,22 @@ public class CEditor extends TextEditor implements ISelectionChangedListener, IC
 		return new ChainedPreferenceStore(stores.toArray(new IPreferenceStore[stores.size()]));
 	}
 
+	/**
+	 * @return <code>true</code> if parser based Content Assist proposals are disabled.
+	 *
+	 * @since 5.0
+	 */
+	public boolean isParserBasedContentAssistDisabled() {
+		return getPreferenceStore().getBoolean(PreferenceConstants.SCALABILITY_PARSER_BASED_CONTENT_ASSIST);
+	}
+	
+	/**
+	 * @return <code>true</code> if the number of lines in the file exceed
+	 * the line number for scalability mode in the preference.
+	 *
+	 * @since 5.0
+	 */
+	public boolean isEnableScalablilityMode() {
+		return fEnableScalablilityMode;
+	}
 }
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditorMessages.properties b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditorMessages.properties
index c45aea72a4b..1d48091aff2 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditorMessages.properties
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/CEditorMessages.properties
@@ -20,6 +20,9 @@ AddIncludeOnSelection.label=Add Include
 AddIncludeOnSelection.tooltip=Add Include Statement on Selection
 AddIncludesOperation.description=Adding include statement
 
+Scalability.message=You are opening a large file.  Turning on scalability mode might help improve editor's performance.  Please see the Scalability preference page under Preferences -> C/C++.
+Scalability.info=Editor Scalability
+Scalability.reappear=Do not show this message again.
 ShowInCView.description=Show the current resource in the C/C++ Projects view
 ShowInCView.label=Show in C/C++ Projects
 ShowInCView.tooltip=Show current resource in C/C++ Projects view
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/SemanticHighlightingManager.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/SemanticHighlightingManager.java
index e15013a102f..58d41f83c79 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/SemanticHighlightingManager.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/SemanticHighlightingManager.java
@@ -32,6 +32,7 @@ import org.eclipse.cdt.ui.text.ICPartitions;
 
 import org.eclipse.cdt.internal.ui.text.CPresentationReconciler;
 import org.eclipse.cdt.internal.ui.text.CSourceViewerConfiguration;
+import org.eclipse.cdt.internal.ui.text.CSourceViewerScalableConfiguration;
 import org.eclipse.cdt.internal.ui.text.IColorManager;
 import org.eclipse.cdt.internal.ui.text.IColorManagerExtension;
 
@@ -300,7 +301,7 @@ public class SemanticHighlightingManager implements IPropertyChangeListener {
 		fColorManager= colorManager;
 		fPreferenceStore= preferenceStore;
 		if (fEditor != null) {
-			fConfiguration= new CSourceViewerConfiguration(colorManager, preferenceStore, editor, ICPartitions.C_PARTITIONING);
+			fConfiguration= new CSourceViewerScalableConfiguration(colorManager, preferenceStore, editor, ICPartitions.C_PARTITIONING);
 			fPresentationReconciler= (CPresentationReconciler) fConfiguration.getPresentationReconciler(sourceViewer);
 		} else {
 			fConfiguration= null;
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.java
index 962774d7b8c..e8343a79ccc 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.java
@@ -367,6 +367,20 @@ public final class PreferencesMessages extends NLS {
 	public static String MarkOccurrencesConfigurationBlock_link_tooltip;
 	public static String MarkOccurrencesConfigurationBlock_markOccurrences;
 	public static String MarkOccurrencesConfigurationBlock_stickyOccurrences;
+	
+	public static String ScalabilityPreferencePage_description;
+	public static String ScalabilityPreferencePage_detection_label;
+	public static String ScalabilityPreferencePage_detection_group_label;
+	public static String ScalabilityPreferencePage_trigger_lines_label;
+	public static String ScalabilityPreferencePage_error;
+	public static String ScalabilityPreferencePage_scalabilityMode_group_label;
+	public static String ScalabilityPreferencePage_scalabilityMode_label;
+	public static String ScalabilityPreferencePage_reconciler_label;
+	public static String ScalabilityPreferencePage_syntaxColor_label;
+	public static String ScalabilityPreferencePage_contentAssist_label;
+	public static String ScalabilityPreferencePage_note;
+	public static String ScalabilityPreferencePage_preferenceOnlyForNewViews;
+
 
 	static {
 		NLS.initializeMessages(BUNDLE_NAME, PreferencesMessages.class);
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.properties b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.properties
index 34c64b612c7..9286ee9a698 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.properties
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/PreferencesMessages.properties
@@ -424,3 +424,19 @@ MarkOccurrencesConfigurationBlock_link= The appearance can be configured on the
 MarkOccurrencesConfigurationBlock_link_tooltip=Show the annotations preferences
 MarkOccurrencesConfigurationBlock_markOccurrences= Mark &occurrences of the selected element in the current file.
 MarkOccurrencesConfigurationBlock_stickyOccurrences= &Keep marks when the selection changes
+
+#Scalability Preferences
+ScalabilityPreferencePage_description= Settings for editor scalability
+ScalabilityPreferencePage_detection_group_label= Scalability mode detection
+ScalabilityPreferencePage_detection_label= Alert me when scalability mode should be turned on
+ScalabilityPreferencePage_trigger_lines_label= Enable scalability mode options when the number of lines in the file is more than:
+ScalabilityPreferencePage_error=Value must be an integer between {0} and {1}.
+ScalabilityPreferencePage_scalabilityMode_group_label= Scalability mode settings 
+ScalabilityPreferencePage_scalabilityMode_label= Enable all scalability mode options
+ScalabilityPreferencePage_reconciler_label= Disable editor reconciling (Outline view, semantic highlighting and editor folding will also be disabled)
+ScalabilityPreferencePage_syntaxColor_label= Disable syntax coloring in editor
+ScalabilityPreferencePage_contentAssist_label= Disable parsing-based content assist proposals
+ScalabilityPreferencePage_note=Note:
+ScalabilityPreferencePage_preferenceOnlyForNewViews=Some options do not affect opened views
+ScalabilityPreferencePage_error=Value must be an integer between {0} and {1}.
+
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/ScalabilityPreferencePage.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/ScalabilityPreferencePage.java
new file mode 100644
index 00000000000..6005090c2d6
--- /dev/null
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/preferences/ScalabilityPreferencePage.java
@@ -0,0 +1,298 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 2008 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *     Anton Leherbauer (Wind River Systems)
+ *******************************************************************************/
+
+package org.eclipse.cdt.internal.ui.preferences;
+
+import java.text.MessageFormat;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+
+import org.eclipse.jface.dialogs.Dialog;
+import org.eclipse.jface.dialogs.IDialogConstants;
+import org.eclipse.jface.preference.FieldEditor;
+import org.eclipse.jface.preference.IPreferenceStore;
+import org.eclipse.jface.preference.IntegerFieldEditor;
+import org.eclipse.jface.preference.PreferencePage;
+import org.eclipse.jface.preference.StringFieldEditor;
+import org.eclipse.jface.resource.JFaceResources;
+import org.eclipse.jface.util.IPropertyChangeListener;
+import org.eclipse.jface.util.PropertyChangeEvent;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.events.SelectionEvent;
+import org.eclipse.swt.events.SelectionListener;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Button;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.ui.IWorkbench;
+import org.eclipse.ui.IWorkbenchPreferencePage;
+import org.eclipse.ui.PlatformUI;
+
+import org.eclipse.cdt.ui.CUIPlugin;
+import org.eclipse.cdt.ui.PreferenceConstants;
+import org.eclipse.cdt.utils.ui.controls.ControlFactory;
+
+import org.eclipse.cdt.internal.ui.ICHelpContextIds;
+import org.eclipse.cdt.internal.ui.wizards.dialogfields.Separator;
+
+public class ScalabilityPreferencePage extends PreferencePage implements
+		IWorkbenchPreferencePage {
+	
+	// Files with this number of lines will trigger scalability mode
+	private IntegerFieldEditor fLinesToTrigger;
+	
+	private Button fAlertMe;
+	
+	private Button fEnableAll;
+	
+	private Button fReconciler;
+	
+	private Button fSyntaxColor;
+	
+	private Button fContentAssist;
+	
+	private Map<Object, String> fCheckBoxes= new HashMap<Object, String>();
+	
+	/**
+	 * List of master/slave listeners when there's a dependency.
+	 * 
+	 * @see #createDependency(Button, String, Control)
+	 */
+	private ArrayList<Object> fMasterSlaveListeners= new ArrayList<Object>();
+	
+	public ScalabilityPreferencePage() {
+		setPreferenceStore(PreferenceConstants.getPreferenceStore());
+		setDescription(PreferencesMessages.ScalabilityPreferencePage_description); 
+	}
+	
+	/**
+	 * Creates a button with the given label and sets the default configuration data.
+	 */
+	private Button createCheckButton( Composite parent, String label, String key ) {
+		Button button = new Button( parent, SWT.CHECK | SWT.LEFT );
+		button.setText( label );
+		// FieldEditor GridData
+		GridData data = new GridData();
+		button.setLayoutData( data );
+		fCheckBoxes.put(button, key);
+		return button;
+	}
+	
+	private void initFields() {
+		IPreferenceStore prefs=getPreferenceStore();
+
+		Iterator<Object> iter= fCheckBoxes.keySet().iterator();
+		while (iter.hasNext()) {
+			Button b= (Button) iter.next();
+			String key= fCheckBoxes.get(b);
+			b.setSelection(prefs.getBoolean(key));
+		}
+		
+        // Update slaves
+        iter= fMasterSlaveListeners.iterator();
+        while (iter.hasNext()) {
+            SelectionListener listener= (SelectionListener)iter.next();
+            listener.widgetSelected(null);
+        }
+        fLinesToTrigger.setStringValue(Integer.toString(prefs.getInt(PreferenceConstants.SCALABILITY_NUMBER_OF_LINES)));	
+	}
+
+	/*
+	 * @see PreferencePage#createControl(Composite)
+	 */
+	@Override
+	public void createControl(Composite parent) {
+		super.createControl(parent);
+		PlatformUI.getWorkbench().getHelpSystem().setHelp(getControl(), ICHelpContextIds.SCALABILITY_PREFERENCE_PAGE);
+	}	
+
+	/*
+	 * @see PreferencePage#createContents(Composite)
+	 */
+	@Override
+	protected Control createContents(Composite parent) {
+		initializeDialogUnits(parent);
+		int nColumns= 1;
+				
+		Composite composite= new Composite(parent, SWT.NONE);
+		GridLayout layout= new GridLayout();
+		layout.marginHeight= convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_MARGIN);
+		layout.marginWidth= 0;
+		layout.numColumns= nColumns;
+		composite.setLayout(layout);
+		
+		GridData data = new GridData();
+		data.verticalAlignment = GridData.FILL;
+		data.horizontalAlignment = GridData.FILL;
+		composite.setLayoutData( data );
+		
+		createDetectionSettings(composite);
+
+		new Separator().doFillIntoGrid(composite, nColumns);	
+		
+		createScalabilityModeSettings(composite);
+
+		new Separator().doFillIntoGrid(composite, nColumns);	
+		
+		String noteTitle= PreferencesMessages.ScalabilityPreferencePage_note;
+		String noteMessage= PreferencesMessages.ScalabilityPreferencePage_preferenceOnlyForNewViews; 
+		Composite noteControl= createNoteComposite(JFaceResources.getDialogFont(), composite, noteTitle, noteMessage);
+		GridData gd= new GridData(GridData.HORIZONTAL_ALIGN_FILL);
+		gd.horizontalSpan= 2;
+		noteControl.setLayoutData(gd);
+		
+		initFields();
+		
+		Dialog.applyDialogFont(composite);
+		return composite;
+	}
+	
+	/**
+	 * Creates composite group and sets the default layout data.
+	 * 
+	 * @param parent
+	 *            the parent of the new composite
+	 * @param numColumns
+	 *            the number of columns for the new composite
+	 * @param labelText
+	 *            the text label of the new composite
+	 * @return the newly-created composite
+	 */
+	private Composite createGroupComposite( Composite parent, int numColumns, String labelText ) {
+		return ControlFactory.createGroup( parent, labelText, numColumns );
+	}
+	
+	/**
+	 * Create the view setting preferences composite widget
+	 */
+	private void createDetectionSettings( Composite parent ) {
+		Composite group = createGroupComposite( parent, 1, PreferencesMessages.ScalabilityPreferencePage_detection_group_label );
+		fAlertMe = createCheckButton(group, PreferencesMessages.ScalabilityPreferencePage_detection_label,PreferenceConstants.SCALABILITY_ALERT);
+	}
+	
+	/**
+	 * Create the view setting preferences composite widget
+	 */
+	private void createScalabilityModeSettings( Composite parent ) {
+		Composite group = createGroupComposite( parent, 1, PreferencesMessages.ScalabilityPreferencePage_scalabilityMode_group_label );
+		
+		Composite comp = ControlFactory.createComposite( group, 2 );
+		fLinesToTrigger = new IntegerFieldEditor( PreferenceConstants.SCALABILITY_NUMBER_OF_LINES, PreferencesMessages.ScalabilityPreferencePage_trigger_lines_label, comp);
+		GridData data = (GridData)fLinesToTrigger.getTextControl( comp ).getLayoutData();
+		data.horizontalAlignment = GridData.BEGINNING;
+		data.widthHint = convertWidthInCharsToPixels( 11 );
+		fLinesToTrigger.setPage( this );
+		fLinesToTrigger.setValidateStrategy( StringFieldEditor.VALIDATE_ON_KEY_STROKE );
+		fLinesToTrigger.setValidRange( 1, Integer.MAX_VALUE );
+		String minValue = Integer.toString( 1 );
+		String maxValue = Integer.toString( Integer.MAX_VALUE );
+		fLinesToTrigger.setErrorMessage( MessageFormat.format(PreferencesMessages.ScalabilityPreferencePage_error, new String[]{ minValue, maxValue } ) );
+		fLinesToTrigger.load();
+		fLinesToTrigger.setPropertyChangeListener( new IPropertyChangeListener() {
+
+			public void propertyChange( PropertyChangeEvent event ) {
+				if ( event.getProperty().equals( FieldEditor.IS_VALID ) )
+					setValid( fLinesToTrigger.isValid() );
+			}
+		} );
+		
+		new Separator().doFillIntoGrid(group, 1);
+		
+		fEnableAll = createCheckButton(group, PreferencesMessages.ScalabilityPreferencePage_scalabilityMode_label, PreferenceConstants.SCALABILITY_ENABLE_ALL);
+		fReconciler = createCheckButton(group, PreferencesMessages.ScalabilityPreferencePage_reconciler_label, PreferenceConstants.SCALABILITY_RECONCILER);
+		createDependency(fEnableAll, PreferenceConstants.SCALABILITY_ENABLE_ALL, fReconciler);
+		
+		fContentAssist = createCheckButton(group, PreferencesMessages.ScalabilityPreferencePage_contentAssist_label, PreferenceConstants.SCALABILITY_PARSER_BASED_CONTENT_ASSIST);
+		createDependency(fEnableAll, PreferenceConstants.SCALABILITY_ENABLE_ALL, fContentAssist);
+		
+		fSyntaxColor = createCheckButton(group, PreferencesMessages.ScalabilityPreferencePage_syntaxColor_label, PreferenceConstants.SCALABILITY_SYNTAX_COLOR);
+		createDependency(fEnableAll, PreferenceConstants.SCALABILITY_ENABLE_ALL, fSyntaxColor);
+	}
+	
+	private static void indent(Control control) {
+		GridData gridData= new GridData();
+		gridData.horizontalIndent= 20;
+		control.setLayoutData(gridData);		
+	}
+	
+	private void createDependency(final Button master, String masterKey, final Control slave) {
+		indent(slave);
+		boolean masterState= getPreferenceStore().getBoolean(masterKey);
+		slave.setEnabled(!masterState);
+		
+		if (masterState) {
+			((Button)slave).setSelection(masterState);
+		}
+		
+		SelectionListener listener= new SelectionListener() {
+			public void widgetSelected(SelectionEvent e) {
+				slave.setEnabled(!master.getSelection());
+				if (master.getSelection()) {
+					((Button)slave).setSelection(master.getSelection());
+				}
+			}
+
+			public void widgetDefaultSelected(SelectionEvent e) {}
+		};
+		master.addSelectionListener(listener);
+		fMasterSlaveListeners.add(listener);
+	}
+	
+	/*
+	 * @see IWorkbenchPreferencePage#init(IWorkbench)
+	 */
+	public void init(IWorkbench workbench) {
+	}
+	
+	/*
+	 * @see IPreferencePage#performOk()
+	 */
+	@Override
+	public boolean performOk() {
+		IPreferenceStore prefs= getPreferenceStore();
+		Iterator<Object> iter= fCheckBoxes.keySet().iterator();
+		while (iter.hasNext()) {
+			Button b= (Button) iter.next();
+			String key= fCheckBoxes.get(b);
+			prefs.setValue(key, b.getSelection());
+		}
+		prefs.setValue(PreferenceConstants.SCALABILITY_NUMBER_OF_LINES, fLinesToTrigger.getIntValue());
+		CUIPlugin.getDefault().savePluginPreferences();
+		return super.performOk();
+	}	
+	
+	/*
+	 * @see PreferencePage#performDefaults()
+	 */
+	@Override
+	protected void performDefaults() {
+		IPreferenceStore prefs= getPreferenceStore();
+
+		Iterator<Object> iter= fCheckBoxes.keySet().iterator();
+		while (iter.hasNext()) {
+			Button b= (Button) iter.next();
+			String key= fCheckBoxes.get(b);
+			b.setSelection(prefs.getDefaultBoolean(key));
+		}
+		
+        // Update slaves
+        iter= fMasterSlaveListeners.iterator();
+        while (iter.hasNext()) {
+            SelectionListener listener= (SelectionListener)iter.next();
+            listener.widgetSelected(null);
+        }
+        fLinesToTrigger.setStringValue(Integer.toString(prefs.getDefaultInt(PreferenceConstants.SCALABILITY_NUMBER_OF_LINES)));	
+	}
+}
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerConfiguration.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerConfiguration.java
index 202ca02bca2..44674ef020a 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerConfiguration.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerConfiguration.java
@@ -107,35 +107,35 @@ import org.eclipse.cdt.internal.ui.typehierarchy.THInformationProvider;
  */
 public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	
-	private ITextEditor fTextEditor;
+	protected ITextEditor fTextEditor;
 	/**
 	 * The document partitioning.
 	 */
-	private String fDocumentPartitioning;
+	protected String fDocumentPartitioning;
 	/**
 	 * The code scanner.
 	 */
-	private AbstractCScanner fCodeScanner;
+	protected AbstractCScanner fCodeScanner;
 	/**
 	 * The C multi-line comment scanner.
 	 */
-	private ICTokenScanner fMultilineDocCommentScanner;
+	protected ICTokenScanner fMultilineDocCommentScanner;
 	/**
 	 * The C single-line comment scanner.
 	 */
-	private ICTokenScanner fSinglelineDocCommentScanner;
+	protected ICTokenScanner fSinglelineDocCommentScanner;
 	/**
 	 * The C string scanner.
 	 */
-	private AbstractCScanner fStringScanner;
+	protected AbstractCScanner fStringScanner;
 	/**
 	 * The preprocessor scanner.
 	 */
-	private AbstractCScanner fPreprocessorScanner;
+	protected AbstractCScanner fPreprocessorScanner;
 	/**
 	 * The color manager.
 	 */
-	private IColorManager fColorManager;
+	protected IColorManager fColorManager;
 	
 	/**
 	 * Creates a new C source viewer configuration for viewers in the given editor
@@ -238,7 +238,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	/**
 	 * Initializes the scanners.
 	 */
-	private void initializeScanners() {
+	protected void initializeScanners() {
 		fStringScanner= new SingleTokenCScanner(getTokenStoreFactory(), ICColorConstants.C_STRING);
 	}
 
@@ -397,7 +397,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	 * @return the settings
 	 * @since 4.0
 	 */
-	private IDialogSettings getSettings(String sectionName) {
+	protected IDialogSettings getSettings(String sectionName) {
 		IDialogSettings settings= CUIPlugin.getDefault().getDialogSettings().getSection(sectionName);
 		if (settings == null)
 			settings= CUIPlugin.getDefault().getDialogSettings().addNewSection(sectionName);
@@ -529,7 +529,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	 * @return the indent prefixes
 	 * @see #getIndentPrefixes(ISourceViewer, String)
 	 */
-	private String[] getIndentPrefixesForSpaces(int tabWidth) {
+	protected String[] getIndentPrefixesForSpaces(int tabWidth) {
 		String[] indentPrefixes= new String[tabWidth + 2];
 		indentPrefixes[0]= getStringWithSpaces(tabWidth);
 		
@@ -552,7 +552,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	 * @param count	the space count
 	 * @return the string with the spaces
 	 */
-	private static String getStringWithSpaces(int count) {
+	protected static String getStringWithSpaces(int count) {
 		char[] spaceChars= new char[count];
 		Arrays.fill(spaceChars, ' ');
 		return new String(spaceChars);
@@ -563,7 +563,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	 * no ICProject could be determined
 	 * @return
 	 */
-	private ICProject getCProject() {
+	protected ICProject getCProject() {
 		ITextEditor editor= getEditor();
 		if (editor == null)
 			return null;
@@ -751,7 +751,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
 	 * @return an information control creator
 	 * @since 5.0
 	 */
-	private IInformationControlCreator getInformationPresenterControlCreator(ISourceViewer sourceViewer) {
+	protected IInformationControlCreator getInformationPresenterControlCreator(ISourceViewer sourceViewer) {
 		return new IInformationControlCreator() {
 			public IInformationControl createInformationControl(Shell parent) {
 				return new DefaultInformationControl(parent, true);
@@ -827,7 +827,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
      * Creates control for outline presentation in editor.
      * @return Control.
      */
-    private IInformationControlCreator getOutlineControlCreator() {
+    protected IInformationControlCreator getOutlineControlCreator() {
         final IInformationControlCreator conrolCreator = new IInformationControlCreator() {
             /**
              * @see org.eclipse.jface.text.IInformationControlCreator#createInformationControl(org.eclipse.swt.widgets.Shell)
@@ -845,7 +845,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
      * Creates control for outline presentation in editor.
      * @return Control.
      */
-    private IInformationControlCreator getHierarchyControlCreator() {
+    protected IInformationControlCreator getHierarchyControlCreator() {
         final IInformationControlCreator conrolCreator = new IInformationControlCreator() {
             /**
              * @see org.eclipse.jface.text.IInformationControlCreator#createInformationControl(org.eclipse.swt.widgets.Shell)
@@ -929,7 +929,7 @@ public class CSourceViewerConfiguration extends TextSourceViewerConfiguration {
      * Creates control for macro exploration in editor.
      * @return Control.
      */
-    private IInformationControlCreator getMacroExplorationControlCreator() {
+    protected IInformationControlCreator getMacroExplorationControlCreator() {
         final IInformationControlCreator conrolCreator = new IInformationControlCreator() {
             public IInformationControl createInformationControl(Shell parent) {
                 return new CMacroExpansionExplorationControl(parent);   
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerScalableConfiguration.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerScalableConfiguration.java
new file mode 100644
index 00000000000..b45f6a5284d
--- /dev/null
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/CSourceViewerScalableConfiguration.java
@@ -0,0 +1,53 @@
+/*******************************************************************************
+ * Copyright (c) 2008 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.cdt.internal.ui.text;
+
+import org.eclipse.jface.preference.IPreferenceStore;
+import org.eclipse.jface.text.presentation.IPresentationReconciler;
+import org.eclipse.jface.text.reconciler.IReconciler;
+import org.eclipse.jface.text.source.ISourceViewer;
+import org.eclipse.ui.texteditor.ITextEditor;
+
+import org.eclipse.cdt.ui.PreferenceConstants;
+
+import org.eclipse.cdt.internal.ui.editor.CEditor;
+
+/**
+ * Configuration for an <code>SourceViewer</code> which shows C/C++ code.
+ * It turns off some editor features when scalability mode options are enabled.
+ */
+public class CSourceViewerScalableConfiguration extends
+		CSourceViewerConfiguration {
+
+	public CSourceViewerScalableConfiguration(
+			IColorManager colorManager, IPreferenceStore preferenceStore,
+			ITextEditor editor, String partitioning) {
+		super(colorManager, preferenceStore, editor, partitioning);
+	}
+	
+	@Override
+	public IReconciler getReconciler(ISourceViewer sourceViewer) {
+		if (((CEditor)getEditor()).isEnableScalablilityMode() && fPreferenceStore.getBoolean(PreferenceConstants.SCALABILITY_RECONCILER))
+    		return null;
+		return super.getReconciler(sourceViewer);
+	}
+	
+	/**
+     * @see org.eclipse.jface.text.source.SourceViewerConfiguration#getPresentationReconciler(org.eclipse.jface.text.source.ISourceViewer)
+	 */
+    @Override
+	public IPresentationReconciler getPresentationReconciler(ISourceViewer sourceViewer) {
+    	if (((CEditor)getEditor()).isEnableScalablilityMode() && fPreferenceStore.getBoolean(PreferenceConstants.SCALABILITY_SYNTAX_COLOR))
+    		return null;
+		return super.getPresentationReconciler(sourceViewer);
+	}
+}
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/CContentAssistInvocationContext.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/CContentAssistInvocationContext.java
index 32647ae46f8..6dc1e38f766 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/CContentAssistInvocationContext.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/CContentAssistInvocationContext.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2007 IBM Corporation and others.
+ * Copyright (c) 2005, 2008 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -28,6 +28,7 @@ import org.eclipse.cdt.ui.PreferenceConstants;
 import org.eclipse.cdt.ui.text.contentassist.ContentAssistInvocationContext;
 import org.eclipse.cdt.ui.text.contentassist.ICEditorContentAssistInvocationContext;
 
+import org.eclipse.cdt.internal.ui.editor.CEditor;
 import org.eclipse.cdt.internal.ui.text.CHeuristicScanner;
 import org.eclipse.cdt.internal.ui.text.Symbols;
 
@@ -61,7 +62,7 @@ public class CContentAssistInvocationContext extends ContentAssistInvocationCont
 	 * @param viewer the viewer used by the editor
 	 * @param offset the invocation offset
 	 * @param editor the editor that content assist is invoked in
-	 * @param isAutoActivated  inidicates whether content assist was auto-activated
+	 * @param isAutoActivated indicates whether content assist was auto-activated
 	 */
 	public CContentAssistInvocationContext(ITextViewer viewer, int offset, IEditorPart editor, boolean isCompletion, boolean isAutoActivated) {
 		super(viewer, offset);
@@ -111,6 +112,14 @@ public class CContentAssistInvocationContext extends ContentAssistInvocationCont
 	}
 		
 	public IASTCompletionNode getCompletionNode() {
+		
+		//for scalability
+		if (fEditor != null && fEditor instanceof CEditor) {
+			CEditor editor = (CEditor)fEditor;
+			if (editor.isEnableScalablilityMode() && editor.isParserBasedContentAssistDisabled())
+				return null;
+		}
+		
 		if (fCNComputed) return fCN;
 		
 		fCNComputed = true;
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/PreferenceConstants.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/PreferenceConstants.java
index 0b2fa6d1c2d..f01bb8b8c4b 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/PreferenceConstants.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/PreferenceConstants.java
@@ -1300,6 +1300,66 @@ public class PreferenceConstants {
 	 */
 	public static final String EDITOR_STICKY_OCCURRENCES= "stickyOccurrences"; //$NON-NLS-1$
 
+	/**
+	 * A named preference that controls whether all scalability mode options should be turned on.
+	 * <p>
+	 * Value is of type <code>Boolean</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_ENABLE_ALL = "enableScalabilityOptions"; //$NON-NLS-1$
+
+	/**
+	 * A named preference that controls whether the editor's reconciler is disabled.
+	 * <p>
+	 * Value is of type <code>Boolean</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_RECONCILER = "reconciler"; //$NON-NLS-1$
+	
+	/**
+	 * A named preference that controls whether syntax coloring is disabled.
+	 * <p>
+	 * Value is of type <code>Boolean</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_SYNTAX_COLOR = "syntaxColor"; //$NON-NLS-1$
+
+	/**
+	 * A named preference that controls whether parser-based content assist proposals are disabled.
+	 * <p>
+	 * Value is of type <code>Boolean</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_PARSER_BASED_CONTENT_ASSIST = "cdtContentAssist"; //$NON-NLS-1$
+
+	/**
+	 * A named preference that controls whether users should be notified if scalability mode should be turned on.
+	 * <p>
+	 * Value is of type <code>Boolean</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_ALERT = "detectScalability"; //$NON-NLS-1$
+	
+	/**
+	 * The size of the file that will trigger scalability mode
+	 * <p>
+	 * Value is of type <code>int</code>.
+	 * </p>
+	 *
+	 * @since 5.0
+	 */
+	public static final String SCALABILITY_NUMBER_OF_LINES = "numberOfLines"; //$NON-NLS-1$
+
 	/**
 	 * Returns the CDT-UI preference store.
 	 *
@@ -1481,6 +1541,14 @@ public class PreferenceConstants {
 		// mark occurrences
 		store.setDefault(PreferenceConstants.EDITOR_MARK_OCCURRENCES, true);
 		store.setDefault(PreferenceConstants.EDITOR_STICKY_OCCURRENCES, true);
+		
+		//Scalability
+		store.setDefault(PreferenceConstants.SCALABILITY_ALERT, true);
+		store.setDefault(PreferenceConstants.SCALABILITY_NUMBER_OF_LINES, 5000);
+		store.setDefault(PreferenceConstants.SCALABILITY_ENABLE_ALL, false);
+		store.setDefault(PreferenceConstants.SCALABILITY_RECONCILER, false);
+		store.setDefault(PreferenceConstants.SCALABILITY_SYNTAX_COLOR, false);
+		store.setDefault(PreferenceConstants.SCALABILITY_PARSER_BASED_CONTENT_ASSIST, false);
     }