With every new Windows there’s countless rumours (like with every new MSFS update). And even if it’s there and you can measure it, doesn’t mean it’ll stay this way and most likely it won’t make a difference IRL.
That said: I stick to Windows 10. Never change a running system. Especially not if there’s no clear proven advantage. Also: MS pretty consistently proved over the last 30 years that every second Windows version is worse than it’s predecessor just to be followed by a major breakthrough. Windows 3.11 (followed by Windows 95), Windows 98 (followed by 98 SE), Windows ME (followed by XP), Windows Vista (followed by 7), Windows 8 (followed by 10) … I don’t trust them to break the pattern now 