ruby script/plugin install git://github.com/henrik/route_speedup.git

BEFORE: 0.191446860631307 ms/url
AFTER: 0.029847304022858 ms/url
Speed up: 6.4 times

Route recognition is slow due to one-by-one iterating over a whole routeset (each map.resources generates at least 14 routes) and matching weird regexps on each step.

We optimize this by skipping all URI segments that 100% sure can't be matched, moving deeper in a tree of routes (where node == segment) until first possible match is accured. In such case, we start walking a flat list of routes, matching them with accurate matcher.
So, first step: search a segment tree for the first relevant index. Second step: iterate routes starting with that index.

How tree is walked? We can do a recursive tests, but it's smarter: We just create a tree of if-s and elsif-s matching segments.

We have segments of 3 flavors:

1) nil (no segment, route finished)    
2) const-dot-dynamic (like "/posts.:xml", "/preview.:size.jpg")    
3) const (like "/posts", "/comments")    
4) dynamic ("/:id", "file.:size.:extension")    

We split incoming string into segments and iterate over them.
When segment is nil, we drop immediately, on a current node index.
When segment is equal to some const, we step into branch.
If none constants matched, we step into 'dynamic' branch (it's a last).
If we can't match anything, we drop to last index on a level.

Note: we maintain the original routes order, so we finish building steps on a first dynamic segment.

Example. Given the routes:

 0 /posts/    
 1 /posts/:id    
 2 /posts/:id/comments    
 3 /posts/blah    
 4 /users/    
 5 /users/:id    
 6 /users/:id/profile    
 
  request_uri = /users/123    

There will be only 4 iterations:

1) segm test for /posts prefix, skip all /posts/* routes    
2) segm test for /users/    
3) segm test for /users/:id (jump to list index = 5)    
4) full test for /users/:id => here we are!

There is currently no advanced documentation for this plugin.