It is quite simple actually, first, you must acquire the Developer Console by (in-game) going to your keyboard settings > advanced > enable developer console.

Once that is done you can open it with the apostrofe key (the little key above TAB). There, you have to type mat_viewportscale followed by a number from 0 to 1.

1 being 100% and 0.5 being 50%

What that command does? it changes the 3d render resolution, similar to Fortnite. It can be used in VALVe servers and will not put you in risk for a ban for it only affects your graphics.

This command works wonders, i used to play at 30 fps at most in every map, but now, by using 0.5 (50%) i get 80+ in even the most intensive maps like Pier.

I trully hope this helps someone to make the game a bit more playable <3 <3