I’ve tried logging into VRChat recently and it lags my entire PC, it never did this before. the day before from the time of posting this I was able to combat the issue by factory resetting my entire PC and reinstalling windows, but now I haven’t been able to get in, when I checked my performance there is no impact on my GPU or CPU when I launch the game, none at all. It started happening after a popup for the VRChat installation helper came up. ive tried verifying files, unistalling then reinstalling. the only thing thats worked was to factory reset, and thats just get in to the game once then have the same problem.
Run through the steps given here and see if it helps.
Make sure you update your graphics drivers, too.
If you’re on a laptop, make sure the system is set up to use your main GPU for VRChat.