A web cache benchmarking package called Web Polygraph  is used for comparison of caching web proxies. The clients and servers are simulated; the client workload parameters such as hit ratio, cacheability, and response sizes can be specified and server-side delays can be specified. We used the PolyMix-2 traffic model to compare Apache  using UFS and a slightly modified version of Apache using Hummingbird without collocate_files() calls. Due to space considerations of this paper, we only briefly discuss our results.
We used one of our FreeBSD Pentium IIIs for the proxy. We used a number of different client request rates; the following results are for 8 requests/second. We found that the mean response time for hits in the proxy is 14 times smaller with Hummingbird than with UFS, and the median response time for hits is 20 times smaller. The improvement in mean and median response times for proxy misses was much smaller, as expected; Hummingbird is 20% faster than UFS. Since Hummingbird serves proxy hits faster, its request queue is shorter, which in turn, shortens the queue time of proxy misses.