@Unclewebb

I thought it was just a little "bug", didn't know it also decrease performance like that. I was planning to reinstall windows because of the slower performance I somehow get.
It explains a lot.

HPET is enabled in the bios.

Will try to insert /USEPMTIMER in the boot.ini and see if that will solve the problem.
Does the windows timer also infect with msi afterburner or other oc-software related to gpu?