> We forked rails and _practically wrote our own._ We fought against the framework. We deviated from the framework, and we even wondered if rails was right for us at all.
and
> Rails 3 was found to be five times slower than Rails 2
I regularly talk with engineers that worked on that project at GitHub, some are now my coworkers. I know more about this effort than what was said publicly.
> Rails 3 was found to be five times slower than Rails 2
This is a bogus claim. It might have been 5 times slower on some pathological cases, it absolutely wasn't 5 times slower overall.
You are interpreting both links you gave in terrible ways.
It sounds like you’re seeing the pain GitHub suffered through rose colored glasses. The talks about GitHub Rails upgrades say it took years and caused burnout.
The conclusion of Eileen's talk is that by not following with upgrade and essentially forking Rails 2.3 they painted themselves in a corner. They took short term gains, and produced longs term losses. It's a self induced problem.
In the end they upgraded and are now tracking the main branch, so the problem wasn't Rails.