FCPX freezing

Hi

I'm working on a large doc project in sections on my MBP 2.66. Twice in the past week, FCPX would freeze when loading a specific event. In the first case, that event was unneeded so I deleted it, in the second case I trashed prefs and it seems to have resolved that problem for now.

But I was curious what this repeated problem might be indicating.

Is it just because it's a big project?

Would performance improve if I moved media outside the library, specifically, dslr files that get copied into the library because they need the qt wrapper to run in fcpx?

Any other ideas?

best

elmer