Earlier quoted context omitted.
I assume you are limiting your definition of "system-taxing" to playing games specifically? As other people have noted, filesystem performance is often better under Linux. I also will point out that at least some rendering tasks can be faster under Linux as well: http://blog.thepixelary.com/post/167616662857/improving-perf... Just like with the filesystem performance discrepancy, this article seems to point out WDDM…
Using git as a filesystem performance metric is horribly flawed -- git was written from the beginning to perform perfectly on Linux. It's the most native linux application I can think of. (Not because it's using secret system calls, but because its design was vetted and performance tailored for Linux.)
And that can't be fixed without involving 10 different teams and potentially outside partners.
And there's something wrong with the filesystem, which can't be fixed without the same deal except that will definitely require the cooperation of the outside partners because apparently you can write an extension for NTFS and fixing it would break the existing extensions, which Microsoft doesn't have the source for and doesn't ship.
And there's a thousand other paper cuts, and a very large fraction of those would require cross-team coordination and testing, which is a horrible time sink in a large company.
Fundamentally, Windows has poor performance when dealing with lots of little files, which is exactly what compiling large code bases involves. And to top it all off, their build system, conspires against their own OS. You'll get better performance using cmake + ninja (on Windows that is) then you will with cmake + visual studio.
Edit: also as a practical matter, if all my company's code is in git, and all outside code bases I work with are in git, I kinda would like decent git performance regardless of the origins of the tool.
I use windows as an outlook appliance at work, and as a gaming appliance at home. Otherwise I do everything in linux and am much happier.