Season 1 did nothing for me, I managed to try it and the performance was exactly the same, in RedSec too. However I did something that I think is a temporary solution until this incompetent developers listen to us and acknowledge this problem. I deleted the HD Texture packs and the game runs fine now, the FPS drops are a lot more subtle. I actually managed to play the game just fine on Overkill settings in 1080p. Can't really say exactly what kind of performance I am getting because my monitor is capped to 75Hz but at least during combat is way better. I know this might not be a good solution because we have hardware MORE THAN CAPABLE to run this game at max settings without any issue but I promise you that you wont notice the difference at all. Give it a try, delete the texture packs for both multiplayer and RedSec. See it for yourself, it made the game way smoother for me.
By the way, all the tests and screenshots I provided were conducted with the following disabled:
1. HD textures
2. Single-player
3. Single-player HD textures
4. Multiplayer HD textures
So, in my case, this doesn't provide any performance gains. May be noticeable in comparison, but it's not very significant.
