Well I'm gonna be devil's advocate here, I've seen game performance quadruple after a clear reinstall of Windows. So saying that it's all the game's fault isn't exactly true. It can run "ok" under ideal conditions, but still compared to what my rig can pull off in other games it's still pretty horrible.
Honestly it's feels about as good as my phemon II x4 @2.4ghz & GT320 managed at launch, but now i'm running a ryzen 2600 @4.2ghz and a GTX 1070TI. Granted I'm running at 1080p instead of 720p and all details at 5 instead of 4 but you get the idea.
However, I've never had to reinstall windows with any other game to get my FPS back up. So there is something going on with the game, but it's influenced by factors outside of the game.
Side note, 32bit client didn't work for me. Out of sync audio and 5 sec input delays client side. Haven't tried it again since reinstalling, but I'll update my post with the results.