Microsoft engineer explains how Clipboard windows are optimized for best performance

Raymond Chen, a senior engineer at Microsoft, often shares interesting stories about Windows or the company itself. Recently, he revealed interesting information such as why a Janet Jackson song is officially considered a cyber threat to Windows computers, and how system features like APO are used to protect PCs.

In his latest post for Microsoft's The Old New Thing, Chen explains why Windows' default clipboard feature is different — and superior — to other clipboard managers thanks to its asynchronous mechanism, which helps optimize system performance.

What's special about the Windows Clipboard?

Many users wonder: "Why doesn't Clipboard History record very fast changes to the clipboard content?" Chen replied that it is the asynchronous approach that makes the Windows clipboard work more efficiently, avoiding slowing down the system even when the clipboard content changes continuously.

Windows achieves this through two components:

1. AddClipboardFormatListener function : Belongs to the Winuser.h header file, handles user inputs such as keyboard, mouse.
2. WM_CLIPBOARDUPDATE Notification : Identifies the clipboard change notification.

These two API features were introduced with Windows Vista. Chen explains:

The clipboard history service operates asynchronously. It registers for clipboard changes via AddClipboardFormatListener. When it receives a change notification, it updates the history. However, since notifications arrive asynchronously, by the time the service receives the WM_CLIPBOARDUPDATE message, the clipboard may have changed a second time.

This is different from clipboard viewers — which receive a synchronous notification every time the clipboard changes. The downside is that you might 'miss' some changes, but the bigger advantage is that it avoids slowing down or freezing the clipboard.

In doing so, Microsoft has designed even a seemingly simple feature like the clipboard to prioritize operating system performance. Chen asserts that this is proof that the company focuses on the small but important elements to perfect Windows.

Enable Clipboard History

Users can enable this feature via:

1. Settings → System → Clipboard .
2. Shortcut Win + V → Select " Turn on ".

With its smart mechanism, the Windows clipboard is not only convenient but also ensures a smooth experience, even if you copy content continuously.

Kareem Winters

Update 26 May 2025