[MikeSz]

I am back with some partial feedback.
So first of all it looks like the session performance was really bad when I had a PT session on one of my HDD drives.
I have a SDD with Windows&Pro Tools installed on it. I also have two HDD 2-Terabyte drives. One was meant to be for sample libraries that requires much space and the second one (the drive I've recently bought) I intended to be PT sessions drive. In practice it's not working correctly and the performance on this "session drive" is poor. I have copied the session to the "libraries drive" and it is much better there.
The tempo changes however still use a lot of CPU. Disabling tempo sync in delays plugins helped a little bit.
I have disabled C-State Transition in my BIOS but don't see much difference. Avid Windows 10 quide suggests that it should be disabled.

There's still a lot to check so I will come back with more info later.