2 Specific GIT commands that are running during this process are:

git status --porcelain --untracked-files=no --ignore-submodules=dirty

git log --max-count=200  --branches --tags --remotes --full-history --topo-order --decorate=full --date=iso HEAD --

Using the command line from within ST using embedded GIT also produces long delay.

Running these using system GIT, or Putty outside of Sourcetree does not produce this issue.