I totally agree on the testing in isolation helping separate the app from the framework. That said, running “rake environment” shouldn’t do more than require your files…so the fact it’s so slow is somewhat embarrassing IMO and should be sped up. Even if I’m just testing a AR model in isolation, it would be nice to be able to require all my code as quickly as just AR.

If you’re trying to write unit (also known as ‘isolated’) tests, ideally, most things should be tested outside of the rails context anyway. The speed is just one part of it.

That said, testing things that _do_ rely on rails, like integration tests, would still be baller. So thanks for your work. <3 <3 <3

However, let’s be clear. A 6% speed-up is not really significant. If all I did all day was wait for Rails to start up, I’d only save 6% of the day. I don’t even think that would be noticeable. But if I do that only a few times a day (because I use Spork), the gain is obviously much less.

You say “From my experience in doing performance work, there is rarely a silver bullet that will fix performance problems”. I would actually disagree. You don’t solve performance problems by shaving a percent here and a percent there. You solve them by rethinking – by choosing an entirely different way of doing something. That’s my experience most of the time, at least.

But again – very good article.

If this approach proves fruitful, are you thinking of bringing the DTrace probes to 1.9.{2,3} ?

Thank you for sticking with DTrace!