This was promptoglyph's raison d'être, but modern Git has an "fsmonitor" feature that gets you really fast repo status by using a daemon (like Watchman) to keep track of which files might have changed and need another stat(). This system also doesn't like if you murder git status while it's in the middle of doing its thing.
With this feature gone, I should probably revisit zsh's vcs_info and see how it compares (both in output and performance) to this tool.