What was slow?
I'm running Ubuntu on a 9950x3d and 5090 and it is not slow. Games in Steam with Proton are buttery smooth.
One hiccup was I had to disable variable refresh rate because moving the cursor didn't "count" as a reason to update the screen, so moving the cursor on its own (rather than e.g. moving a window) looked choppy.
But a choppy mouse cursor isn't "slow".
Tip: if you have a performance problem, run Claude Code (or an AI agent of your choice) and ask it to investigate.
>What was slow?
Everything, huge input delay in every interaction, clicking on anything, opening menus, typing, tabbing between windows, everything had 1-2s of delay.
>disable variable refresh rate
I think I tried this but dont recall, there were a few things related to monitor refresh I tried that probably included this
Claude Code would probably attach a profiler and take a peek under the hood. Agents are making sysadmin and system introspection way more accessible, and the tools, unlike Windows, are generally command-line, easy for an agent to automate.
In case it helps I have the same experience on Windows right now. :_(