Couple things:<p>* Wow, an O(n^2) require algo. I guess this really drives home that we shouldn't make basic assumptions about the quality of the libs we use without actually looking at them. Great catch.<p>* For all of you waiting for this to be pulled into Ruby master. Why not just patch your copy in the meantime?
Wow, amazing find. I've been struggling with this issue for many months, and I just figured it was rails 3.0 fault for being so big and bloated. Now we find out it's ruby implementation. I really hope this patch makes it in.<p>I've patched my local copy. Feels like I have doubled my computer speed! Seriously though, I can't believe the fix was so easy, and the ruby core hasn't done something about this yet.<p>The last major external fix to ruby was with the REE people, and that <i>still</i> hasn't made it back into MRI. So I'm a bit worried this patch will get rejected and the problem won't be fixed.
I've always thought it would be nice if you could cause Ruby to dump its heap and symbol table to a file, which could then be loaded by other instances of Ruby. So, for example, you could run Ruby, load all of the Rails files, and then save everything, so the next time you want to run Rails, you just have to load one file instead of hitting the file system 2000 times.<p>You could probably also do this by running a Rails instance as a service, and then every time you want to run Rails, you tell the service to fork, and use the forked thread. I think this is how Passenger works actually?
Given the roots in Perl, which has the %INC hash, it's surprising that Ruby started with an array for loaded modules. Can anyone shed some light on this design decision? Surely there was a reason at some point -- and maybe there still is.
If you're not using Bundler and have a simple dependency chain, you can get further improvement from symlinking your gems into a single directory (see <a href="https://gist.github.com/975509" rel="nofollow">https://gist.github.com/975509</a> ).<p>This patch certainly improved my load time tremendously, but the core of the problem still lies with the way rubygems and bundler dump all directories of gems in the load path. The promise of $LOAD_PATH is that all the directories in it will be tried -- the most bang-for-buck optimization is thus minimizing its size.
This patch seems to introduce a bug when loading files with extra periods in the name (I think).<p>My app which includes thinking-sphinx (which has a require '0.9.9'), breaks with it.
Sorry for the snide comment, but if you want to really speed up your Rails, switch to Go, it will compile from scratch and start up your project faster than the ruby interpreter starts up.<p>I used rails in a few projects, and performance was so painful even on pretty good hardware that I said <i>never again</i>. Go on the other hand is pure pleasure.