I'm not surprised that engines that prioritize "fresh" results only turn up claims that the most recent version of Windows is the fastest. Even so the most recent version does have higher system requirements than its predecessor.

Also your search fu is weak. Try: "Windows new version" faster old version

Windows 11 faster than Windows 10:

https://www.tomshardware.com/news/microsoft-details-how-it-m...

Windows 10 faster than Windows 8:

https://edu.gcfglobal.org/en/windows10/windows-10-features/1...

Windows 7 faster than Windows Vista:

https://www.lifewire.com/ways-windows-7-beats-windows-vista-...

To be clear I don't doubt that the claims are technically true. Lies by omission are often technically true.