Follow this guide
https://us.forums.blizzard.com/en/overwatch/t/guide-maximizing-system-performance-for-overwatch-pc
And disable HPET.
Anybody been having performance issues
Also maybe try disabling windows auto-update
And delaying Widows indexing.
https://www.google.com/amp/s/www.pcgamer.com/amp/windows-10-is-learning-a-file-indexing-trick-that-might-make-your-pc-run-faster/