It seems like a very unusual problem...
#1 Maybe this guide to tracking down memory leaks will help.
#2 If you set Opus not to run on startup, then launch it later on after everything has finished booting up, do you still see the problem?
#3 A third thing to try: Does disabling Explorer Replacement make any difference?
(Thanks for trying all these different things, and sorry we're having to try wild guesses to work out what's going on.)