My specs are:
Amd a8-5600k
8gb of 1600mhz ram
Amd radeon hd 7850 1gb

When I play the game with aa x4 or x8 I get around 15 fps while when I play with 2x aa I get around 50 fps, all other settings are high and on accept for vsync. Why does this happen and how do I fix it.

My drivers are the latest version, I have aa set to application controlled in CCC MLaa is on, aa type is adaptive multisampling and turning off MLaa.

Edit: I fixed it by turning off edge detect and changing aa type to regular msaa.