Am I doing something wrong with the asset pipeline?

Question

Since "upgrading" to Rails 3.1 my app is really slow in development mode

(> 30 per request)

I have a lot of images and it seems most of this time-delay is the asset pipeline processing each GET request for each image.

Don't have this problem in Staging or Production mode as the assets are cached etc.

Is there something I haven't been told or is this how we're expected to work now?

Answer 1

Requests can be slow if you have gems or portions of your app that load code at the start of each request - or that merely reference portions of your app, causing much of it to be loaded. For most of these, the autoloader is the prime cause of request delay.

The rails auto-reloader deletes any autoloadable classes/modules/etc at the start of each request, and can cause significant delays at the beginning of each request as Rails reloads all the source files it needs.

You might want to try playing with https://github.com/wavii/rails-dev-tweaks, which gives you granular control over which requests cause the auto-reloader to kick in. This really isn't a fix of the root cause (something is doing extra work at the start of every request that it probably doesn't need to be doing) - but it certainly mitigates most such issues.