Shooting guns causes major fps drop

So recently, I have gotten some weird lags from GMOD. Shooting a weapon (css weapons to be exact + using crowbar) reduce my fps to 1-5.

Specs:
AMD FX 8320
R9 270x 2GB MSI Gaming
8GB 1886mhz RAM

Is there a fix?

Only CS:S weapons? On what base are these CS:S weapons? What gamemode?

TTT, tried different servers. Automatic weapons are worse and sometimes crash my game. I will try some HL2 weapons in a second.

EDIT: I do not get the lag in singleplayer.