Oooh, interesting, so you're right that when I get the lag, there's a lot of CPU usage. Also there was definitely a system update before it started happening - although I can't say exactly when because I wasn't gaming on this system for a few days.
I'm on Mint 22.1 and I've tried uinstalling and reinstalling through the software manager GUI, and I've also tried:
sudo apt purge mesa-vulkan-drivers
sudo apt install mesa-vulkan-drivers
None of that changed the problem. I also made sure I restarted the system.
Am I doing that right? Are there any other steps that I'm missing?