[ReThink]

Ever since I got a fix on my PC that has been having issues with not shutting down by a Windows Support Agent on Monday, GMod has become a very laggy game all of a sudden for me. The support agent that I was getting help from clicked the Video Card in the Device settings ( https://gyazo.com/99d9bfca27a6d08b2215c7db8ffc856d ) to set it for an update by right clicking it, I assumed this was the cause thinking the agent gave it a Windows update, that sets it to a default windows graphics settings..but I'm not sure really if thats the case though. Either way, I wnet to the NVIDIA app and reinstalled a new update for the driver to be updated by that, but it didn't fix the GMod experience at all unforunately, and its literally only for GMod. I tried my other games like PUBG and other high graphic games, and they're playing smoothly, only GMod is having this issue ever since yesterday..If theres anyone that can help me out with this, I would really appreciate any support, because I dooo enjoy getting back into Dinkleberg's TTT server after being away for almost a year, and would hate to have to stop playing again, because it just feels unplayable right now. Just this weekend I was playing it so smoothly to in high settings </3 (yes I've tried turning down the settings) , and my parts for my PC are here: https://pcpartpicker.com/list/h8Gk3F

Are you running any config at all? What are your game settings?

I would verify integrity of game cache from your steam library. 
I would re-install if needed
Couple other things too, but try those first.