FPS difference/drop (Gameplay)

I never had FPS drop,but few patchs ago I'm having like so much FPS drop.It's not cause of my internet or computer.I usually had 120fps on medium without any lags or drop,but now I'm having like 100 fps on low and my FPS drops on 8 every time i use my abillity.I always ask everyone do they got the same problem as I do and they say yes.So I realised I'm definetly not the only one who got this bug.