This is strange - I wasn't expecting such a difference on CPU-only benchmarks. In my experience as a software engineer I find Linux much faster than windows mainly due to the file system being more performant (e.g. the builds run noticeably faster). For CPU-intensive tasks I always thought they were quite similar.

On the other hand since upgrading from 6.6 to 6.11 I noticed a great improvement in UI responsiveness on my old X1 Tablet and I doubt this Ubuntu uses a recent kernel even.

Disclaimer: I haven't used Windows in a long time.