External swf slow playback

Hello :
using the excellent tutorial on preloading and transition for external files (http://www.kirupa.com/developer/mx/preloader_transition.htm)
i have created a main swf file into which i am loading 4 external files. All the external files are large in size (avg.500 k) containing heavy animation and sound. This project is for a CD presentation.

the problem is this: on loading into the main file, the playback speed of external files reduces drastically. The audio plays at a normal speed. However, the animations play very very slowly.

i have tried changing the frame rate in the main file and the external file, but there has been no effect. What am i doing wrong? please help.