Web browser mitigations against CPU vulnerabilities

Please elaborate. What risks am I exposing myself to?

The plan is to not load any sensitive data into memory (no unlocking password manager database etc). Workflow here is: Boot the (sandboxed) game, look up guides online, browse random websites, view youtube videos, reboot when done. I do disable JIT and WASM already, and JS is blocked by default by uBO. I even made a waybar module to scream at me that the CPU mitigations are off so that I don’t forget. The 10-15 FPS gain makes games that are otherwise unplayable, playable.. My CPU is 10 years old.