> Anyway I'm running Linux and put on all (but one) workspaces (or "virtual desktops"), the CPU governor in "powersave" mode, where apparently the CPU doesn't got above 3 Ghz and doesn't go above 45 C. Then on my "dev" workspace, the one where I need the performances, I set the CPU governor to "ondemand"

Is that a feature of a particular desktop or did you write a custom daemon to check on which desktop you are currently? I know that KDE has the concept of activities, which is an even different concept than virtual desktop and would be interesting in that regard.