I was noticing that during certain fights my frames per second went to like 3 frames per second.
So I wanted to improve that.
After some reading up I found a very nice tip, in your rift directory there should be a file rift.cfg
In there there should be MainThreadCPU = 3 . Change that number to 0
Somehow my fps stays in even the busiest fights at 25+ now. (heard that if you put it to 0 your cores work better togteher or something)
I also changed 1 thing ingame that is under settings interface combat. I clicked hide other players FX.
Most people probably knew these tips but for those who dont try it and you will love the results.
Also before the change if I alt tabbed the game would sometimes crash and it took ages before I could do something else now its instant and doesnt crash (knock on wood)