MSYS2. I have WSL and plenty of linux machines but my current side project is native MSYS2 MSVC/cl.exe compiling. Honestly the 10x was conservative. With AV off, on a fairly quality SSD drive running bootstrap on tar (with a good number of gnulib modules) the speed is:
time /WIN64LinuxBuild/build/f_tar_build.sh
./bootstrap: gnulib/gnulib-tool.py --no-changelog --aux-dir=build-aux --doc-base=doc --lib=libgnu --m4-base=m4/ --source-base=gnu/ --tests-base=tests --local-dir=gl --without-tests --symlink --import ...
real 0m35.359s
user 0m4.792s
sys 0m18.634s
vs shell bootstrapper:
real 17m40.540s
user 3m18.828s
sys 8m44.022s
Which is a good 30x speedup.
I will also note that it is running the python version and then running the shell version with no actual module changes. I would assume that to be one of the fastest bootstrapping options.
Obviously WSL with native forking will destroy windows process creation any day, and dealing with it isn't an issue. When you have dozens of processes being created and destroyed every few seconds
https://imgur.com/a/M96S72J it is easy to get the why. I am just mentioning how nice the tool has been when I can use it for packages. As I sometimes was running the bootstrap process a few dozen times a day it would be the difference between waiting and tabbing away to do something else:)