Recent testing revealed that Arch Linux, Pop!_OS, and even Nobara Linux, which is maintained by a single developer, all outstripped Windows for the performance crown on Windows-native games. The testing was run at the high-end of quality settings, and Valve's Proton was used to run Windows games on Linux.
When did ‘rootkit’ come to be a generic term for invasive software? Rootkits are a specific type of thing.
Vanguard, BattlEye, EasyAntiCheat, Ricochet, etc… all run in the Windows Kernel and most, if not all, have the functionality to run arbitrary code, so might as well class them as rootkits.
Anticheats that run in the NT kernel may as well be described as rootkits, especially as they aren’t transparent about exactly what they’re doing. Then there’s the question of what happens if they get compromised