Bundler has always been one of the slowest parts of fiddling with a Rails application, but it's always been a pretty essential tool for any Ruby or Rails application.
A quote from the Github issue:
At one project, which have over 200 gems to be installed, initial bundle -j4 is faster than bundle by about four minutes.
bundle --path sequential 183.03s user 45.13s system 38% cpu 9:55.48 total
bundle --path parallel -j4 234.85s user 50.14s system 77% cpu 6:05.52 total
That's a fantastic improvement and one that will certainly make the lives of many developers just a little bit better.
So if you want to get started using bundler with parallel gem installation, just fire this off in your terminal:
gem install bundler --pre