diff --git a/src/vs/base/browser/ui/tree/tree.ts b/src/vs/base/browser/ui/tree/tree.ts
index 1b020fee6e7fa85437a30b79cb12fe43922801f5..540893da05536d0e4e70d053d694925e0baf6ec6 100644
--- a/src/vs/base/browser/ui/tree/tree.ts
+++ b/src/vs/base/browser/ui/tree/tree.ts
@@ -170,6 +170,9 @@ export class Tree<T> implements IDisposable {
 		onKeyDown.filter(e => e.keyCode === KeyCode.LeftArrow).on(this.onLeftArrow, this, this.disposables);
 		onKeyDown.filter(e => e.keyCode === KeyCode.RightArrow).on(this.onRightArrow, this, this.disposables);
 		onKeyDown.filter(e => e.keyCode === KeyCode.Space).on(this.onSpace, this, this.disposables);
+
+		// TODO@joao cleanup
+		onKeyDown.filter(e => e.keyCode === KeyCode.KEY_A).on(() => this.model.setCollapsedAll(true), null, this.disposables);
 	}
 
 	splice(location: number[], deleteCount: number, toInsert: ISequence<ITreeElement<T>> = Iterator.empty()): Iterator<ITreeElement<T>> {
diff --git a/src/vs/base/browser/ui/tree/treeModel.ts b/src/vs/base/browser/ui/tree/treeModel.ts
index 1116777cb90d38e99e21423649ecfa9caa5d09b8..0fbef7bf5f29b8afa3be3fdae9c5c9ca7b3b08f7 100644
--- a/src/vs/base/browser/ui/tree/treeModel.ts
+++ b/src/vs/base/browser/ui/tree/treeModel.ts
@@ -166,16 +166,16 @@ export class TreeModel<T> {
 	}
 
 	setCollapsed(location: number[], collapsed: boolean): boolean {
-		return this._setCollapsed(location, collapsed);
+		const { node, listIndex, visible } = this.findNode(location);
+		return this._setCollapsed(node, listIndex, visible, collapsed);
 	}
 
 	toggleCollapsed(location: number[]): void {
-		this._setCollapsed(location);
-	}
-
-	private _setCollapsed(location: number[], collapsed?: boolean | undefined): boolean {
 		const { node, listIndex, visible } = this.findNode(location);
+		this._setCollapsed(node, listIndex, visible);
+	}
 
+	private _setCollapsed(node: IMutableTreeNode<T>, listIndex: number, visible: boolean, collapsed?: boolean | undefined): boolean {
 		if (!node.collapsible) {
 			return false;
 		}
@@ -195,13 +195,29 @@ export class TreeModel<T> {
 			const toInsert = updateVisibleCount(node);
 
 			this.list.splice(listIndex + 1, previousVisibleCount - 1, toInsert.slice(1));
+			this._onDidChangeCollapseState.fire(node);
 		}
 
-		this._onDidChangeCollapseState.fire(node);
-
 		return true;
 	}
 
+	// TODO@joao cleanup
+	setCollapsedAll(collapsed: boolean): void {
+		if (collapsed) {
+			const queue = [...this.root.children]; // TODO@joao use a linked list
+			let listIndex = 0;
+
+			while (queue.length > 0) {
+				const node = queue.shift();
+				const visible = listIndex < this.root.children.length;
+				this._setCollapsed(node, listIndex, visible, collapsed);
+
+				queue.push(...node.children);
+				listIndex++;
+			}
+		}
+	}
+
 	isCollapsed(location: number[]): boolean {
 		return this.findNode(location).node.collapsed;
 	}
diff --git a/test/tree/public/index.html b/test/tree/public/index.html
index 3716374c0dea4400f108f153663c6b1a461db0e3..1374fc77837bf11a7c8cbbc6c3c9411fbe560e51 100644
--- a/test/tree/public/index.html
+++ b/test/tree/public/index.html
@@ -44,21 +44,40 @@
 
 			const tree = new Tree(container, delegate, [renderer]);
 
-			const xhr = new XMLHttpRequest();
-			xhr.open('GET', '/api/ls?path=');
-			xhr.send();
-			xhr.onreadystatechange = function () {
-				if (this.readyState == 4 && this.status == 200) {
-					const data = JSON.parse(this.responseText);
+			function setModel(model) {
+				performance.mark('before splice');
+				const start = performance.now();
+				tree.splice([0], 0, model);
+				console.log('splice took', performance.now() - start);
+				performance.mark('after splice');
+			}
 
-					performance.mark('before splice');
-					const start = performance.now();
-					tree.splice([0], 0, [data]);
-					console.log('splice took', performance.now() - start);
-					performance.mark('after splice');
+			switch (location.search) {
+				case '?problems': {
+					const files = [];
+					for (let i = 0; i < 10000; i++) {
+						const errors = [];
 
+						for (let j = 1; j <= (i % 5) + 1; j++) {
+							errors.push({ element: `error #${j}` });
+						}
+
+						files.push({ element: `file #${i}`, children: errors });
+					}
+					setModel(files);
+					break;
 				}
-			};
+				default:
+					const xhr = new XMLHttpRequest();
+					xhr.open('GET', '/api/ls?path=');
+					xhr.send();
+					xhr.onreadystatechange = function () {
+						if (this.readyState == 4 && this.status == 200) {
+							setModel([JSON.parse(this.responseText)]);
+						}
+					};
+			}
+
 		});
 	</script>
 </body>