Firefox browser I assume?
There’s your problem. I daily drive zen, a Firefox based browser but I recommend using a Chromium based browser for playing games. For my game it goes from laggy to forgetting that I was playing in a browser. It is well optimized for browsers, firfox just has bad game performance. I recommend helium because it’s fast, lightweight, degoogled anf of course chromium based. So I switch to that for games.