Define 'tremendous' and present hardware specs and numbers please. Shopify runs varnish (we run varnish on Twitter search) - are speedups coming out of varnish or ngnix for you?

We've done plenty of simulations, load tests, and lots of graphing that shows ngnix's performance gains are negligible given our hardware configuration. We've also got huge dependencies on mod_rewrite right now and didn't want to convert to ngnix for that very reason.

There seems to be this awful myth, completely unsupported by science, that seems to state that unless you're running Rails with ngnix that you're doing the wrong thing. The prevelance of ngnix in the Rails community is astounding.

It's a good server and it certainly has it's place in the world, but it's just not for us and not supported by our benchmarks.

Our web nodes use 6mb of memory for all the web serving each. This frees up gigabytes compared to apache which we can use for more processes ( web and app notes are combined in shopify's case ). The speedup lies there. Added benefit is that nginx somehow manages to terminate SSL with a lot lower CPU load which makes the web/app configuration very appealing. We experimented with terminating SSL in the Ciscos but it seems to be impossible for Cisco that ships a firmware that has this and weighted load balancing working both.

Tremendous, in this case, is because the extremely low resource usage of nginx allowed us to remove an entire layer in our serverfarm flowchart and now we can use our machines much more efficient.