The biggest thing that gems could do to make rubygems faster is to have a registry/database of files for each gem, so that rubygems didn't have to scan the filesystem on every `require` looking for which gem had which file in it.

That would mean that if you edited your gems directly, things would break. Add a file, and it wouldn't get found until the metadata got rehashed. The gem install, uninstall, etc commands would need to be modified to maintain that metadata. But really, you shouldn't be hacking up your gem library like that ith shellcommands anyway (and if you are doing manual surgery, having to regen the metadata isn't really that burdensome).