Could you not make the same argument about JavaScript? JavaScript was pretty slow for many years. Google then put some significant engineering investment into the V8 engine, resulting in a huge increase in JavaScript's performance.
Whilst they are doing their multiyear rewrites, it would be nice if someone could optimise the ruby runtime a bit for them.
But it will take a drastic / complete rewrite of the VM, as it happened to Chrome's and Firefox's JavaScript VMs.
This means many man-years, and a certain break in the continuity, maybe with small but noticeable deviation in the VM's behavior. If we squint just so, we can consider Ruby 3.0 to be such a rewrite.
Crystal is a similar rewrite effort, but a one that isn't trying to stay backwards-compatible.