What are the options that fit this bill? JVM? Go?

This does seem to at least rhyme with twitter's experience, and maybe also github, at least as observed from outside, where a pretty innovative initial product has difficulty progressing after a period of massive scaling.

But also: Is the lesson maybe just knowing when to pivot to more efficient runtime environments? For instance, I believe facebook had a similar experience with php, and pivoted to running it on a custom vm. Did stripe wait too long to do that kind of pivot? Or perhaps you were just there in the middle of it, which is bound to be a messy time.