In Aaron Patterson's recent "Double Dream Hands: So Intense!" presentation[0], he came to the conclusion that Rails 3's slowness is because MRI sucks at GC on a

In Aaron Patterson's recent "Double Dream Hands: So Intense!" presentation[0], he came to the conclusion that Rails 3's slowness is because MRI sucks at GC on a deep stack depth. The average stack depth of Rails 3 applications is ENORMOUS. He mentions in the video that he rewrote the Rack API to pass a mutated var to the next piece of middleware in the Rack chain instead of calling the next middleware and passing an env var to it. The gains were pretty impressive. Hopefully, they make this change to the Rack API for Rails 3.2. That change + the 1.9.3 fix for requiring files[1] should result in much faster overall Rails performance. [0] http://www.youtube.com/watch?v=kWOAHIpmLAI http://www.youtube.com/watch?v=kWOAHIpmLAI [1] http://www.rubyinside.com/ruby-1-9-3-faster-loading-times-require-4927.html http://www.rubyinside.com/ruby-1-9-3-faster-loading-times-re...