Jenkins (Windows) very slow Git fetch

Version 2.6.1 of the Git client for Windows fixes this problem. Now it's running blazingly fast!

I am using the git cmd in Jenkins from:

C:\Program Files\Git\cmd\git.exe

Use Advanced clone behaviors and enable the checkbox for "Do not fetch tags" if you don't need them. Git should still checkout the branch/tag you specify.

Try to enable some of GIT's debug/performance flags to get more info on where things are taking time inside of its plumbing, see https://git-scm.com/book/en/v2/Git-Internals-Environment-Variables. For instance, export GIT_TRACE=1 and also try GIT_TRACE_PERFORMANCE and GIT_TRACE_PACKET.