The taskbar is a horizontal bar at the bottom of your desktop in Windows 11 that shows the Start menu, Search, Task View, Widgets, Chat, File Explorer, Microsoft Edge, and Microsoft Store icons aligned to the center by default. The taskbar corner includes the notification area icons, Quick Settings (Win+A), and Notification Center (Win+N) with the clock and calendar.
When you hover the pointer over an icon on the taskbar with an open window, there is a delay milliseconds you have to wait before seeing the thumbnail preview(s) of the open window(s).
If you like, you can change the hover delay time to how many milliseconds you want.
A shorter delay time will have taskbar thumbnail previews show faster when hovering on a taskbar icon.
A longer delay time will cause taskbar thumbnail previews to take longer before showing when hovering on a taskbar icon. If you set a long enough delay, it will effectively disable showing taskbar thumbnail previews when hovering on a taskbar icon.
This tutorial will show you how to change the hover delay time to show taskbar thumbnail previews for your account in Windows 10 and Windows 11.
The hover delay time will not affect click/tap on the taskbar icon to see thumbnail previews.
EXAMPLE: Taskbar thumbnail preview
Open Registry Editor (regedit.exe).
Navigate to the key below in the left pane of Registry Editor. (see screenshot below)
Do step 4 (change) or step 5 (default) below for what you would like to do.
If you don't have a ExtendedUIHoverTime DWORD, then right click or press and hold on an empty area in the right pane of the Advanced key, click/tap on New and DWORD (32-bit) Value, type ExtendedUIHoverTime, and press Enter.
If you use a very long delay time (ex: 10000 milliseconds), it will effectively disable showing taskbar thumbnail previews when hovering on a taskbar icon.
Close Registry Editor.
Either restart the explorer process, sign out and sign in, or restart the computer to apply.