Why HN was slow and how Rtm fixed it

HN only supports 20 req per second???

flat files, no database

Maybe that's just for dynamic pages. Probably most of the most popular pages are cached and wouldn't be considered in that 20 req/sec. Just my own wild guess though.

That's not the bottleneck. Essentially there's an in-memory database (known as hash tables). Stuff is lazily loaded off disk into memory, but most of the frequently needed stuff is loaded once at startup.

The bottleneck is the amount of garbage created by generating pages. IIRC there is some horrible inefficiency involving UTF-8 characters.

See the second paragraph.

perhaps continuations could be used more judiciously as well

Are you using any sort of in-memory fragment caching? That seems like it might reduce some render overhead.

A great deal, and it does.

That's 0.05 second for a single request: actually pretty good.