springとbootsnapの違い
Note: Bootsnap and Spring are orthogonal tools. While Bootsnap speeds up the loading of individual source files, Spring keeps a copy of a pre-booted Rails process on hand to completely skip parts of the boot process the next time it's needed. The two tools work well together, and are both included in a newly-generated Rails applications by default.
事前に Rails を起動しておいて、そのプロセスから fork して rails c とかすると早い