I have to agree with this. If you have to process 10k submissions in a very short space of time, why have overhead of storing it in the db right then and there

I have to agree with this. If you have to process 10k submissions in a very short space of time, why have overhead of storing it in the db right then and there when you can asynchronously process it later. If you want something interesting to work on, you could have nginx for the front end (faster than lighttpd), accept a form submission which gets written to disk and maybe pop an id on a key-value store like redis, and another poller app in ruby which pops id's off the queue and processes the files on disk.