Most timing codes in Flash games are based on the timing of the on movie_clip.enterframe() event, which means that the movie_clip contains two frames and switches back and fourth at a globally specified frame rate (typically 12 frames/second).
Every 1/12 of a second, the movie clip changes frames and triggers the sequence actions which appear to be calculated continuously.
If your computer speed effects the ability of the flash game to change the frame of movie_clip, then the on movie_clip.enterframe() event occurs on intervals with variation from 1/12 of a second.
