Low GPU usage and unchanging low fps

[Ohrange]

Has anyone experienced unchanging low fps (no matter the settings) and low GPU usage? It seems when things get hectic or a slight bit crowded my GPU usage will crash and so will my FPS, I'm getting fps as low as 15 and as high as 90. ( lower being more frequent than high). At this point the instability is more annoying that the low fps. I love this game, and what it stands for but I can't deal with this anymore so I'm hoping someone has an idea or something that has worked for them.

I've been playing since launch, so no experience in beta but I have been reading a lot into this and it seems like it's a known newer issue with a small group of players, some with set ups way better than mine still getting FPS lower than 60.

Here is a list of things I have tried so far:

1. Played with in game settings (I'm aware of the fps cap setting, that v-sync caps you at 60 and the "physics" setting is known to cause lag.)

2. Played with task manager priority and affinity.

3. Played with hyper threading and other CPU settings.

4. Played with the game's profile and over clock settings with NVIDIA Inspector

5. I've cleaned and checked for over heating, my gpu and cpu temperatures are perfect.

6. And I have also played with my NVIDIA settings to make sure everything is aimed towards quality and not power saving.

I don't know guys, I'm really running out of options and it's starting to lean towards bad optimization, which is weird because I also hear a lot of people praising how well the game runs for them..

Also, I have never had this issue with other games, I run modern MMOs and AAA games with at least 60fps frequently.

edit: I forgot to mention, Windows 10 x64

8gbs of ram, i7-3770 OCed to 4.0, and a GTX 660.