We don't see the exact numbers on the technical side, and my hunch is that pretty much all of the 500ms was saved because of client side optimization.
He mentions spriting some images, that only saves several HTTP requests, often translating to 200-3000ms quicker total load time. (Note that we're talking about full page load times, from the first DNS query to DOM ready.)
I agree Ruby is terribly slow at initializing, but it is not going to be the bottleneck when you run your own dedicated boxes (and 37signals does).
Good job on increasing the conversion rate, by the way.
Edit: Also, it doesn't matter if you precache or cache on-the-fly. You should be serving the homepage from memory (and any static pages for that matter).
He mentions spriting some images, that only saves several HTTP requests, often translating to 200-3000ms quicker total load time. (Note that we're talking about full page load times, from the first DNS query to DOM ready.)
I agree Ruby is terribly slow at initializing, but it is not going to be the bottleneck when you run your own dedicated boxes (and 37signals does).
Good job on increasing the conversion rate, by the way.
Edit: Also, it doesn't matter if you precache or cache on-the-fly. You should be serving the homepage from memory (and any static pages for that matter).