i played multiple Matches before w/o any Problem - then i got Attica and i immediately had Lagspikes throughout the whole Match, checked Task Manager and the Game was using up 100% of my CPU. Second Match i got Attica again, turned down the Terran Displacement Quality 'cause i read that is causing issues but - same problem persisted.
Then i got another Map (Campania) and it all worked fine again, turned the Terrain Stuff back again but worked all fine. Next Match Golden Quarry all worked fine.