Why is my animation so slow on Win XP ?

[jbv]

Hi list,

I have a stack that begins with a (rather complex)
800x600 animation : controls moving around the
screen, blendlevel of various images (gifs & pngs
with transparency) changing slowly, etc...
The whole thing is controled by messages being
sent to the card 20 times per second
(send "next_frame" to this cd in 0.02 second).

Everything runs fine & smoothly on MacOS 9.
but on Win XP, it gets 5 to 10 times slower...
The app seems to have especially hard times
with modifying blendlevel of gifs or pngs...

The most surprising part of the story is that the
Mac is a G3 / 300 MHz, while the Win box runs
at 1.5 GHz...
Another surprising point is that at times (roughly
1 time out of 10) the Win stack runs OK (as fast
as the Mac version)...

I'm somewhat puzzled, as I'm used to the fact
that standalones run usually significantly faster
& smoother on Win...

Any idea ?

Thanks,
JB