Fps drop ingame

While in the lobby my fps is fine, however whenever I start to play a game my fps drops to like 15-35 and I have no idea what is wrong.

My dxdiag result on pastebin: /vJKgaB6Y

I have the exact same problem and still haven’t found a solution. My PC can handle it as I have:
I7-9700K
GeForce RTX 2080.
I get the normal 60 fps in lobby and max fps it says I can get is 400+ but in game im getting 20-40 fps literally unplayable. I haven’t changed anything but just re installed the game. if anyone has any clue what to do just hmu with the solution

This post might help: