Reset a branch to a previous commit
git reset --hard <old-commit-id>
git push -fGet rid of old branches
The command git remote prune origin --dry-run lists branches that can be deleted/pruned on your local. An option --dry-run is needed.
Fix slow and buggy repos
git gc(man page) runs a number of housekeeping tasks, such as compressing filerevisions (to reduce disk space and increase performance) and removing unreachable objects which may have been created from prior invocations ofgit add.git repack(man page) re-organize existing packs into a single, more efficient pack.
Clone a git repo with limited history
Git’s shallow clone option allows you to pull down only the latest n commits of the repo’s history.
git clone --depth [depth] [remote-url]
example: git clone --depth 100 https://github.com/myaccount/myrepo.git