It usually depends on the "Skip Frames" button at the lower right.  If this button is
turned on, Poser skips through the frames to get as close as possible to the
proper frame rate.   If "Skip Frames" is off, Poser draws every frame.  In this case
a very simple scene may be able to play at the proper rate, but a complex scene
will take too long to render even in Preview mode.  (For example, a big scene may
take 1/4 second to draw in Preview mode.  This would mean an effective rate
of 4 FPS, which is 6 times slower than the expected 24 FPS.)

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