In my opinion, any empirical comparisons tend to be inaccurate, or rather, maybe incomplete is the best word.
We may have some bias and wrongly believe something runs faster on Linux than on Windows. That being said, and having used both Linux and Windows for decades, I was impressed with Windows 10’s performance visually, until something changed. I was using Windows 10 and Manjaro/Arch Linux side by side at the end of 2017 and I couldn’t really decide on a clear winner. They looked both equally snappy and therefore I checked some benchmarks that confirmed my expectations back then.
Fast forward to early 2018, when the Meltdown/Spectre Vulnerabilities arose and then suddenly, after the initial mitigations, I started noticing some hiccups affecting only Windows 10. I’m talking about small delays that weren’t there before and which I could never link to the said vulnerabilities’ mitigations. Nevertheless, they started precisely by that time and Linux stayed as snappy as before.
By that time I went back to using Manjaro Linux as my sole desktop OS once again, ditching dual booting and I couldn’t be happier. These vulnerabilities affect mostly I/O heavy tasks and transitions between user and kernel mode. Further, one of the mitigations used by Linux, called retpolines, is reportedly more efficient and as far as I know, couldn’t be used by Windows, as it requires every user land application to be recompiled to support it fully, not just the kernel. This could be done trivially by any Linux distro, but you cannot expect every Windows binary out there to be easily recompiled right away.
The Meltdown/Spectre fixes could have played a role, but there’s nothing like running benchmarks, like for instance this one:
Regarding the filesystem, Linux is always miles ahead:
However when it comes to x264 encoding for instance, Windows leads: