Slow images in NT/W2k/XP

I have an app which loads a proprietry file containing a large number of jpeg images and displays them. The images are decompressed and displayed in standard TImages.
If I run the app under W95/W98 etc I can display up to about 40 images/sec.  If I run it under NT/W2k/XP it slows to about 2 or 3 images/sec. This happens on many different machines including some with very fast processors and high power graphics cards. You can see the images repainting on the screen - it's horrible.
The original app was written in Delphi3. I have just converted it to D6 and compiled it on a W2k machine and it is still exactly the same.
Is there some trick and/or setting to make, either to the OS or to the app or component, to make Timages work faster with NT etc?

This is really bugging me - 200 points to the winner.

Regards,  John
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jellisonAsked:
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SteveWaiteConnect With a Mentor Commented:
Do you do that in OnPaint?

You say you can see it painting the images, is that flashing or the pixels slowly updating.
I'm thinking along the lines of windows doing loads of unneccesary repaints.

I usually BitBlt() to a TPaintBox because I think TImage is intended to keep the picture where TPaintBox must be updated.

Regards,
Steve
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ginsonicCommented:
listening
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SteveWaiteCommented:
Sounds like too many events setting off.
How are you painting?

Regards,
Steve
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jellisonAuthor Commented:
I first decompress the jpeg into a hidden image. Then I check the jpeg comment data embedded in it before copying it to a visible image by doing

ImageN.Picture := HiddenImage.Picture;

Regards,  John
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jellisonAuthor Commented:
Just tidying up. Haven't solved it yet but I will post another question in a different way.
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SteveWaiteCommented:
Thanks! only wish I could help further. I will keep an ey out for the next q.
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