Microsoft KB Archive/322724

= PRB: Poor Video Performance on Compatible Bitmaps After a Video Mode Change =

Article ID: 322724

Article Last Modified on 7/22/2004

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APPLIES TO


 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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This article was previously published under Q322724



SYMPTOMS
You may experience severe video performance degradation after you perform a video mode change when compatible bitmaps are involved.



CAUSE
The BitBlt operations from the screen to a compatible bitmap in the application take a lot longer to complete after you perform a video mode change. This is because all compatible bitmaps are converted to system device-independent bitmaps (DIBs). The system DIBs are no longer in the video memory; therefore, you experience the delay in the completion of the BitBlt operations in the application.



RESOLUTION
To resolve this issue, restart the application after the video mode change takes effect. When the application is restarted, it re-creates the compatible bitmaps, which then reside in the video memory. A better way to handle this situation is to watch for WM_DISPLAYCHANGE messages, and then re-create any compatible bitmaps that the application needs.

Keywords: kbprb kbdisplay KB322724

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