diff --git a/src/vs/code/electron-main/windows.ts b/src/vs/code/electron-main/windows.ts
index 073f7dc441ff44e97f689bb61a70b2a8fb74100b..8ecf84999102342b1d4d802ab7c40d0245aa111e 100644
--- a/src/vs/code/electron-main/windows.ts
+++ b/src/vs/code/electron-main/windows.ts
@@ -1326,7 +1326,17 @@ export class WindowsManager implements IWindowsMainService {
 		}
 
 		// Handle untitled workspaces with prompt as needed
-		e.veto(this.workspacesManager.promptToSaveUntitledWorkspace(this.getWindowById(e.window.id), workspace));
+		e.veto(this.workspacesManager.promptToSaveUntitledWorkspace(this.getWindowById(e.window.id), workspace).then(veto => {
+			if (veto) {
+				return veto;
+			}
+
+			// Bug in electron: somehow we need this timeout so that the window closes properly. That
+			// might be related to the fact that the untitled workspace prompt shows up async and this
+			// code can execute before the dialog is fully closed which then blocks the window from closing.
+			// Issue: https://github.com/Microsoft/vscode/issues/41989
+			return TPromise.timeout(0).then(() => veto);
+		}));
 	}
 
 	public focusLastActive(cli: ParsedArgs, context: OpenContext): CodeWindow {
diff --git a/src/vs/editor/common/model/textModel.ts b/src/vs/editor/common/model/textModel.ts
index 27c58c24d2e628f9421da9067aeb372d6a093a2e..5a05edb5ccc1fac4c6f8e89b37fe0af3e170b814 100644
--- a/src/vs/editor/common/model/textModel.ts
+++ b/src/vs/editor/common/model/textModel.ts
@@ -38,7 +38,7 @@ import { PieceTreeTextBufferBuilder } from 'vs/editor/common/model/pieceTreeText
 import { ChunksTextBufferBuilder } from 'vs/editor/common/model/chunksTextBuffer/chunksTextBufferBuilder';
 
 // Here is the master switch for the text buffer implementation:
-const USE_PIECE_TREE_IMPLEMENTATION = false;
+const USE_PIECE_TREE_IMPLEMENTATION = true;
 const USE_CHUNKS_TEXT_BUFFER = false;
 
 function createTextBufferBuilder() {