Activity Stream UI sometimes slow in git - it makes calls to git remote show.

The Activity Stream needs to know the name of the default branch (e.g., trunk, main, master, default, etc). In git, we don't necessarily know this upfront and may need to make a remote call "git remote show" (see GitContext.java:getMainBranchName and SpecificRepositorySearcher.java for context).
This means waiting as long as ~15s per repository (seen in a support case) for a slow connection when you first hit an Activity Stream, and potentially every hour afterwards (since we only cache this for an hour).