While the hosted virtual environments work just fine, trying to run on a self-hosted windows runner fails today if gnu tar is not already on the path (e.g. via a mingw install or similar).

On newer versions of Windows, BSD tar is included, so you get an error like:

C:\Windows\system32\tar.exe -cz --force-local -f C:/Users/zarenner/actions-runner/_work/_temp/8b5e8d5e-a823-42dd-a103-7b47503f2fdb/cache.tgz -C C:/Users/zarenner/actions-runner/_work/zarenner-testperf/zarenner-testperf .
tar.exe: Option --force-local is not supported
Usage:
  List:    tar.exe -tf <archive-filename>
  Extract: tar.exe -xf <archive-filename>
  Create:  tar.exe -cf <archive-filename> [filenames...]
  Help:    tar.exe --help
##[warning]The process 'C:\Windows\system32\tar.exe' failed with exit code 1

Note that this isn't especially high priority since:

1. People don't usually wipe self-hosted runners each run making hosted caching less important, and
2. Unless the self-hosted runner happens to co-located with the caching service storage, significant performance gains are unlikely anyways