Hello,
I've recently updated my OS to win 10 and I started noticing some fps drops after I alt+tab (doesn't happen 100% of the time). It also happens when I change areas, then I have to alt+tab again (sometimes multiple times) to get my game running 100% again.
Mist 60 fps (locked) using 70-80% of GPU.
After alt+tab...
Mist 37-40 fps and using 99% of GPU.
note: This issue wasn't happening on win 8.1.