Rails3 development mode performance issues


I'm developing an app on Rails3. Development mode performance seems to
be pretty poor, especially on pages involving AJAX and several
queries. On an AJAX search page, result requests take anything from
500-600ms to return from the local machine. According to the
development log, the ActiveRecord portion of the requests is taking <
30ms, so I'm pretty sure it's not inefficient queries.

I'm running Apache/Passenger/Postgresql on the same machine, which is
a 4ghz Core2Duo with plenty of RAM. In production mode on the same
database, these requests take 20-25ms. Obviously it's like comparing
oranges and apples, but is there any way to optimize development mode
somehow, without enabling class caching or anything overboard like
that which would require regular restarts?

Rails is reloading all of your app's code for each request, that takes
time. Stuff like http://github.com/thedarkone/rails-dev-boost does
exist, don't know if they work on rails 3.