I have noted that when a Virtual Machine is actively going to disk, the entire OSX machine can be left at a standstill. This means that any process that may be running (even a web browser, such as safari) can hang out waiting until that disk access slows down or stops within the VM. If you're running a 5 minute disk based process, it can take 5 minutes for anything on the OSX side to come back alive again. There should be a knob for controlling disk access priority -- it seems that Parallels may be sacrificing OSX disk access for parallels VM performance. Golan.
I have commented on this several times. I haven't seen the code, but I'd assume that it's not a priority problem, but a blocking I/O problem. If it were priority, the other operations continue as expected, albeit slowly. However, with blocking I/O, nothing can happen until the synchronous code is done executing. This is particularly bad during the VM bootup process. While parallels does boot very fast, I'd rather be able to use the rest of the computer while I'm waiting for it.
