We had a long time AVID editor working on an episode and that project get to about 285MB before it began to be really problematic. It was slow to load and everything before that but at that size it became unstable and it took me 3 or 4 hours of opening and crashing and BBOD watching before I was able to get the project down to two or three smaller projects.
I keep all my sequence projects under 80MB and let my source projects creep up to 150MB. I have my projects arranged so that the source project doesn't need saving and I actually work with Autosave off (the Horror!) and have trained my command-I fingers to respond to seeing a good scene go by after a bunch of hacking. I don't recommend this unless you are prepared for it.
Keep your project size down, especially if you have less than 2GIG Ram in your system.
We have 4.5 which exceeds the maximum that FCP can address while leaving extra for other applications.
ak
ak
Sleeplings, AWAKE!