Well, if you compare my result with yours you can see that my fps are quite stable throughout the whole game, while yours show extreme differences between min and avg (and the max ones as well).
I assume you still have gibs enabled, and this is what probably causes your framedrops. So just disable them. They're useless anyway, unless you are a great splatter fan.
You can find that point in the 'Player Setup' menue (at the bottom, right side)