diff --git a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/ToolItemUpdater.java b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/ToolItemUpdater.java
index 9f888cb2f46..e55f8643bc9 100644
--- a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/ToolItemUpdater.java
+++ b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/ToolItemUpdater.java
@@ -47,11 +47,13 @@ void removeItem(AbstractContributionItem item) {
 	}
 
 	public void updateContributionItems(Selector selector) {
+		boolean queued = false;
 		boolean doRunNow = false;
 		for (final AbstractContributionItem ci : itemsToCheck) {
 			if (ci.getModel() != null && ci.getModel().getParent() != null) {
 				if (selector.select(ci.getModel())) {
 					itemsToUpdateLater.add(ci);
+					queued = true;
 					if (timestampOfEarliestQueuedUpdate == 0) {
 						timestampOfEarliestQueuedUpdate = System.nanoTime();
 					}
@@ -61,14 +63,16 @@ public void updateContributionItems(Selector selector) {
 						// again and again in less than given DELAY frequency. TimerExec would then
 						// never be executed.
 						doRunNow = true;
-					} else {
-						Display.getDefault().timerExec(DELAY, this);
 					}
 				}
 			} else {
 				orphanedToolItems.add(ci);
 			}
 		}
+		if (queued && !doRunNow) {
+			// one timer for the whole batch, rescheduling it per item only costs time
+			Display.getDefault().timerExec(DELAY, this);
+		}
 		if (!orphanedToolItems.isEmpty()) {
 			itemsToCheck.removeAll(orphanedToolItems);
 			orphanedToolItems.clear();
diff --git a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchPage.java b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchPage.java
index 11073f4f801..325e6d283fa 100644
--- a/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchPage.java
+++ b/bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchPage.java
@@ -42,6 +42,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.IdentityHashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
@@ -1061,12 +1062,14 @@ public EditorReference createEditorReferenceForPart(final MPart part, IEditorInp
 	private List<EditorReference> getOrderedEditorReferences() {
 
 		List<EditorReference> editorRefs = new ArrayList<>();
+		Set<EditorReference> seen = new HashSet<>();
+		Map<MPart, EditorReference> referencesByModel = getEditorReferencesByModel();
 		List<MPart> visibleEditors = modelService.findElements(window, CompatibilityEditor.MODEL_ELEMENT_ID,
 				MPart.class);
 		for (MPart editor : visibleEditors) {
 			if (editor.isToBeRendered()) {
-				EditorReference ref = getEditorReference(editor);
-				if (ref != null && !editorRefs.contains(ref)) {
+				EditorReference ref = referencesByModel.get(editor);
+				if (ref != null && seen.add(ref)) {
 					editorRefs.add(ref);
 				}
 			}
@@ -1075,23 +1078,36 @@ private List<EditorReference> getOrderedEditorReferences() {
 		return editorRefs;
 	}
 
+	/**
+	 * Maps the model element of every editor reference of this page to its
+	 * reference, so that callers can resolve many parts without rescanning the
+	 * reference list for each one.
+	 */
+	private Map<MPart, EditorReference> getEditorReferencesByModel() {
+		Map<MPart, EditorReference> referencesByModel = new IdentityHashMap<>(editorReferences.size());
+		for (EditorReference ref : editorReferences) {
+			referencesByModel.putIfAbsent(ref.getModel(), ref);
+		}
+		return referencesByModel;
+	}
+
 	List<EditorReference> getSortedEditorReferences() {
 		return getSortedEditorReferences(false);
 	}
 
 	private List<EditorReference> getSortedEditorReferences(boolean allPerspectives) {
+		Map<MPart, EditorReference> referencesByModel = getEditorReferencesByModel();
 		List<EditorReference> sortedReferences = new ArrayList<>();
+		Set<EditorReference> seen = new HashSet<>();
 		for (MPart part : activationList) {
-			for (EditorReference ref : editorReferences) {
-				if (ref.getModel() == part) {
-					sortedReferences.add(ref);
-					break;
-				}
+			EditorReference ref = referencesByModel.get(part);
+			if (ref != null && seen.add(ref)) {
+				sortedReferences.add(ref);
 			}
 		}
 
 		for (EditorReference ref : editorReferences) {
-			if (!sortedReferences.contains(ref)) {
+			if (seen.add(ref)) {
 				sortedReferences.add(ref);
 			}
 		}
@@ -1101,13 +1117,17 @@ private List<EditorReference> getSortedEditorReferences(boolean allPerspectives)
 			int scope = allPerspectives ? WINDOW_SCOPE : EModelService.PRESENTATION;
 			List<MPart> placeholders = modelService.findElements(window, CompatibilityEditor.MODEL_ELEMENT_ID,
 					MPart.class, null, scope);
+			// only rendered placeholders are valid references
+			Set<MPart> rendered = Collections.newSetFromMap(new IdentityHashMap<>(placeholders.size()));
+			for (MPart placeholder : placeholders) {
+				if (placeholder.isToBeRendered()) {
+					rendered.add(placeholder);
+				}
+			}
 			List<EditorReference> visibleReferences = new ArrayList<>();
 			for (EditorReference reference : sortedReferences) {
-				for (MPart placeholder : placeholders) {
-					if (reference.getModel() == placeholder && placeholder.isToBeRendered()) {
-						// only rendered placeholders are valid references
-						visibleReferences.add(reference);
-					}
+				if (rendered.contains(reference.getModel())) {
+					visibleReferences.add(reference);
 				}
 			}
 
@@ -2318,32 +2338,36 @@ private IWorkbenchPartReference[] getSortedParts(boolean editors, boolean views,
 		}
 
 		List<IWorkbenchPartReference> sortedReferences = new ArrayList<>();
+		Set<IWorkbenchPartReference> seen = new HashSet<>();
 		IViewReference[] viewReferences = getViewReferences(allPerspectives);
 		List<EditorReference> editorReferences = getSortedEditorReferences(allPerspectives);
 
-		activationLoop: for (MPart part : activationList) {
-			if (views) {
-				for (IViewReference ref : viewReferences) {
-					if (((ViewReference) ref).getModel() == part) {
-						sortedReferences.add(ref);
-						continue activationLoop;
-					}
-				}
+		Map<MPart, IWorkbenchPartReference> viewsByModel = new IdentityHashMap<>(viewReferences.length);
+		if (views) {
+			for (IViewReference ref : viewReferences) {
+				viewsByModel.putIfAbsent(((ViewReference) ref).getModel(), ref);
+			}
+		}
+		Map<MPart, IWorkbenchPartReference> editorsByModel = new IdentityHashMap<>(editorReferences.size());
+		if (editors) {
+			for (EditorReference ref : editorReferences) {
+				editorsByModel.putIfAbsent(ref.getModel(), ref);
 			}
+		}
 
-			if (editors) {
-				for (EditorReference ref : editorReferences) {
-					if (ref.getModel() == part) {
-						sortedReferences.add(ref);
-						break;
-					}
-				}
+		for (MPart part : activationList) {
+			IWorkbenchPartReference ref = viewsByModel.get(part);
+			if (ref == null) {
+				ref = editorsByModel.get(part);
+			}
+			if (ref != null && seen.add(ref)) {
+				sortedReferences.add(ref);
 			}
 		}
 
 		if (views) {
 			for (IViewReference ref : viewReferences) {
-				if (!sortedReferences.contains(ref)) {
+				if (seen.add(ref)) {
 					sortedReferences.add(ref);
 				}
 			}
@@ -2351,7 +2375,7 @@ private IWorkbenchPartReference[] getSortedParts(boolean editors, boolean views,
 
 		if (editors) {
 			for (EditorReference ref : editorReferences) {
-				if (!sortedReferences.contains(ref)) {
+				if (seen.add(ref)) {
 					sortedReferences.add(ref);
 				}
 			}