FPS drop to 1-20 everytime I killed a mob

After the latest patch, killing a mob pack will drop my fps to 10-20. Making it totally unplayable.

Used to have a constant FPS in town or even during breach(40-60fps).

Any idea how to fix this?

http://imgur.com/a/ZmSS2

EDIT, updated with dxdiag info.
http://pastebin.com/5g2pC0qQ

make sure to post your DXDiag so people looking at your thread can have more information to help you.