Large FLA file is causing Flash to run slowly

I can't figure out why this is happening, or how to stop this.

I have a very long animation I'm working on, and the size of the FLA file is really big.

(I have Flash MX 2004.)

Every time I do something, like edit a frame or go into a symbol to edit it or create a new keyframe, and as of recently even editing ActionScript, flash freezes for a few seconds.

I'm not sure exactly what causes Flash to eat up my CPU; my computer doesn't freeze as Flash is trying to edit or open something; it seems to happen immediately afterwards.

This is becomming unbearable. At this rate, it's going to take me a month to get an hour's worth of work done. Does anyone know anything I can do to improve the performance of Flash, or to stop Flash from lagging so much?

Upgrade your CPU and grab more memory lol :)