Kalista appears to be causing serious FPS fluctuations

My friend and I each bought kalista yesterday. We played two games together, each playing her once. In both games (on SR Beta) my FPS would start fluctuating making the game choppy and near unplayable. Normally, my FPS is around 300 laning, and 180 in team fight scenarios. When kalista is in the game, my FPS fluctuate between 60 and 180 every second or so. Very aggravating. I have played numerous games on SR Beta without kalista in the game, and no FPS issues. I tried capping FPS at 60 and turning on vsync. The FPS monitor in the game stayed at 60, but the choppiness continued anyway. Thoughts?

Rig: i5 3570k 16 gigs ram AMD HD 7950 gfx card