When there are more than one flash clip playing at same time with images into swf archive, playback fps drop dramatically but only on flash clips, not on other video formats that are playing in others layers. The fps counter not notice of this low playback, keep the rate of other clips (avi, mov, live cams).
Is not ever but occur many times.
Composition is 640x960 (2 layers at 640x480 one up, other down) every layer out on one video output only.
FPS rate are from 55 to 45.