Hello Snoopey, i have also the same issue by upgrading from win 8.1 Pro 64bit to win 10 pro 64bit. (Since Upgrade i have also low fps in every game.) The only thing that works for me is to use the "-flush" command in game. After that, artefacts disapear but fps don´t increase. Rig: AMD Phenom II X4 955 3.2 GHZ GTX 660 8 GB Ram