Multiprocessor de-activated in studio setup

I am working on a project with a lot of instrumentracks and midi tracks, those are mostly freezed after recording.
Buffer is set on 256 and Asioguard is on and so is Multiprocessing actived in the Studio setup.
Now I constantly havind pops and clicks and realtime peaks in the cpu meter.
But…I did a test with the multiprocessor(and therefore also Asio guard) de-activated and now the I can work agaon. The RT meter is never going to the max and pops anymore.
I always thought the Multiproccessor should be actived, and while working on audiotracks and mixing I never had this problems.
Any thoughts on this would be welcome

just testes the same project in Cubase 10, there it is exactly the other way around, and therefore it never occured to me in the past:
With Multiproc. and Asioguiard ON > things run smoothly. When I turn those OFF i get high realtime CPU and pops and clicks.