I see that you’re running 7.5 on 8.1 and everything seems to be in order. So I gotta ask: did you at any point have any visual issues with mixer console?
Once I’ve upgraded to 7.5 from 7, my main “sporadic cpu spikes” issue seems to have been addressed. Well, I wasn’t really able to fully verify that as at this point I chose not to start any new projects due to a newly discovered issue I have with mixer console. Every time I toggle between Project Window and Mixer console, Cubase resets width of individual mixer channels to default size. Might not be a big deal to some, but it is extremely annoying to me. And realizing that I never had any visual glitches in C7 makes it even worse.
I did try all the suggested fixes that I could find on this forum and few others, but without any luck so far. I’m looking forward to 7.5.20. Hopefully update will fix it. However I won’t hold my breath as I didn’t see anything specific in the list of fixes of the upcoming update.