Is triple buffering, vsync, FreeSync, or GSync enabled? That stuff prevents tearing but can add a bit of lateny.
Is Nvidia Reflex enabled?
Try to get some tool that tracks your FPS throughout the arena match. Maybe the average FPS is 300 but you get spikes where it drops much lower, maybe due to badly coded addons?
You’re not, it has been looking choppy compared to older versions for quite some time even when you’re playing at higher FPS when you compare to older versions of the game.
Because the game is overdesigned, so many variables, so much to figure out, so much to code and get on both aspects (input and output) that the game is optimised as best as it can be, but in general it is absolutely appalling.
Just look at trying to zone into Valdrakken and then compare to how smooth Classic/Wrath is.