I've upgraded several Rails apps from ~>2.3.0 through to 4.0. I saw performance regressions around Rails 3, and they've subsequently disappeared when upgrading

I've upgraded several Rails apps from ~>2.3.0 through to 4.0. I saw performance regressions around Rails 3, and they've subsequently disappeared when upgrading to 3.2 and 4.0 - the latter in general being much faster. I have to wonder what you're doing that's giving you an average of 480ms? Have you stripped out middleware you're not using? Have you looked into exactly where the time is going? There are so many places to start, it's hard to offer much concrete advice.