There "shouldn't" be a size limit (besides memory size) but your earlier comment suggests that there might be a problem with some versions. (?) Are you sure you're waiting long enough? A long time ago - when the "multipass" stuff was first added - I was using a Nintendo emulator as a test case. Took about an hour and a half! If some versions work and some don't, it could be a bug.
Debs? Did you have something to say?
Best,
Frank