Happy new year to all!
I am pleased to announce Calfpath, a fast Ring-based routing library that supports flexible, à la carte request matching. It supports both macro-based and data-driven routing.
At SAP Concur we have been using this library for over 3 years in production on REST(ish) API servers. During early 2015 when we were using Compojure, we found it was causing 4% of the total internal latency. That is when we switched to Calfpath - roughly an order of magnitude faster. The benchmarking code is included in the repo - however, you should probably test against your own use-case to determine suitability.
The API has matured quite a bit over time and is now more stable than ever before. Among downsides, as of now Calfpath is neither bi-directional, nor ClojureScript ready.
I would love to receive your feedback and answer any questions. Please let me know what you think.