Your doubts re completely unfounded. Linux was set up in 5 mins, I just installed OpenSUSE, installed Steam and ran the games, since the AMD/Intel drivers are included in the kernel.
On Windows I had to set up for like 45 mins until the installation and all the updates and drivers were done.
Any scheduler optimisation ? Cryotool ? Feral Gamemode ? Linux has its own bunch of optimisation tools.
But I'd still doubt a 100% difference, unless you played a game with known problems under Proton. For my own experience after almost a year playing on Linux I gained between 5% and 20%, depending on the game.
That's the other issue. "Depending on the game" 60% of all titles doesnt work on Linux and the rest 40% works badly. There is about a handful of games that could perform better than windows but with windows everything works. I am not trying to defend windows, fuck Microsoft. I just want you guys to stop with this delusion that linux is superior. In most ways it is but in the way thag counts the most, windows is still superior.
Windows is closed source so it has to do extra stuff to hide it's internal behavior. Linux isn't. This allows better drivers in Linux. This means in some cases emulating windows games on Linux is literally faster. You don't have to emulate the entire system, only the parts you need to run the game on your computer.