(Steam version) I get slow downs randomly that are cured on alt tab. Have less than hour left to get a refund

Killer Instinct on Steam
1

I get slow downs randomly that are cured on alt tab. Have less than an hour left to get a refund.

Phenom 965 ii 4x4ghz
8gb ddr3 1600 mhz
1060 3gb
windows 7 64bit pro sp1

Also crashes on exit