Exporting your symbols would be a good idea. Assuming an empty FLA doesn't slow you down, you could expect the same speed performance.
That said, a compiled FLA with library assets creates for a larger swf. Everything (usually) must load before you see anything, whereas as dynamically loaded assets are more responsive, as it offloads the wait time to after StageReady
.
Two other ways to speed things up:
- CS6 uses a reengineered framework that's 64 bit. It's less buggy too.
- A new computer never hurts. ;)