On an average day I probably spend 30 minutes to an hour of each day waiting on environment loading, depending on the task. Big restructurings and big new features tend to take a lot of test iterations.
Now that I do the numbers my time sunk on this is simply staggering.
/obvious
Why is this not the #1 priority for the MRI team?
Step 1: Learn to speak Japanese. Step 2: Express that the startup speed of a project that, IIRC, none of them use and that doesn't pay the bills at their day jobs is Really Really Important To White People and that anything which compromises its utility -- which should be checked exhaustively at every release -- should block shipping.
I use Rails, and love Rails, but back home Rails is not yet the core Ruby use case, not by a long shot. Rails has peculiar needs with regards to typical Ruby applications, and a certain portion of the developer community feels that people who write themselves peculiar needs can write their own solutions to them. (i.e. "If they're going to run tests every few seconds and load a thousand files every time it runs... why is poor performance our problem again?")
Apologies for being a wee bit snippy but variations on this discussion have come up before.
While the MRI team benefits enormously from the international success of Ruby that is largely attributable to Rails, you are right that they are not technically obligated to promptly fix egregious performance regressions. A certain portion of the developer community might feel that it is irresponsible not to support your user base.