Framedrops when using mouse in lategame

As the title says: I get huge microstutters when i use the mouse in the late game. It's especially terrifying when you jump around an enemy, look at him and then there is a huge stutter.
When I circle the mouse fast, the fps drops down to 15!

My Rig:
Intel 2500k @ 4,1Ghz
GTX 570
8 GB Ram

Graphics: Texture middle, AF and multicore rendering on, the rest is off or on lowest.
I have a screenshot of the profile while circling the mouse:
http://cloud-2.steampowered.com/ugc/1081141376191941184/2EE67E736B575619F13FBB61966CFAF9C786D1C7/