I've never done that, but thanks for the heads up on that.

It sounds like Carrara may be handling memory cleanup with a garbage collector running on a separate thread... if they're not forcing a collection and waiting for it to finish every so often, then a long, heavy render could conceivably chew up memory before the GC (usually a low priority thread in most designs) gets to it.

GC's are great for programmers, because you rarely have memory leaks with them, but they're not necessarily the most efficient way to handle memory from a performance point of view.