I have seen the same problem in another posts in this forum. When I insert plugins (Vst2 and Vst3) in my tracks, audio or instrument tracks the performance metter shows an increase of 8-15% increase per plugin. That makes Cubase almost useless with 4 or 5 tracks with inserts. I tried the latest 10.5.20 update and the problem is still the same.
I am very dissapointed as this does not happen with Reaper or FL Studio. Does anyone knows the solution? I have Windows 8.1 I know 8.1 is out of support which is also anoying and unfare in my opinion.