Sounds alot like what I have going on. I was getting some decent frame rates heck I hit 52 at one time I have never seen that. Went from Freeport to commonlnads and it diped to 28, then nek forest where it really lagged I got a steady 2 then eventually came back up to 15. Once I hit lavastorm it was just bad, I did hit 20's but in the middle of a solo shard run it crashed to desktop but this time no error message. I heard the windows beep, then the screen froze and I saw my desktop but with no windows background. Didn't get it back until I did a restart.
Fix something that needs to be fixed, instead of messing with stuff that actualy works. Game ran fine until the last update. I'm a tad miffed, can't play a game anymore that use to work fine. I mean come on... I use to play for 4 to 5 hours now I'm lucky to get 20 minuets.