I'd say about 1000 or so. Best way to tell is by using the debugger and try to patch it when the frame rate starts dropping. One thing about MMF is that if it's struggling to work on your comp, chances are it'll be struggling to work on someone else's comp as well, whether it's 50% better or worse.
I used the colorizer object to make a major colorizing effect on my game. Since it lagged so badly when it use, I only created the object while using it. Strangely, by slowing the frame rate down, it added a bit of a bullet time effect
Disclaimer: Any sarcasm in my posts will not be mentioned as that would ruin the purpose. It is assumed that the reader is intelligent enough to tell the difference between what is sarcasm and what is not.