Routing there is also O(n) in the number of handlers, if I'm reading the code right. If you can't match a URL to a Handler in less than O(log n) in the number of handlers, you're doing it wrong. Programs that are growing in size usually do so because they are actually being used, so as your need for the framework to scale grows, you have to waste time re-engineering efficient routing into your existing program, and usually in a panic or crisis situation. Both Snap and Yesod do this right.

G