BL2 framerate drops in hectic combats

Hi devs, pls fix damned framerate drops in hectic combats(I mean fight with large groups of enemies at the same time)in open area. Even thought after combats when the dead bodyes are everywhere. 60fps is cool and the game looks nice, but everytime when I go to fight with large group of enemies the framerate drops appears. I can’t enjoy playing coz of that :frowning: Please allow us to set function 30fps/60fps lock. Thx
Edit: I have hundreds hours played BL2 on xbox360 and I can say that smooth 30fps is better than 60fps with drops! I want enjoy this best game on my ps4, pls