All tests were made on 2x Intel Xeon X5570 (16 cores assigned for VirtualBox) + 32 GB RAM assigned for Virtualbox + 3x SSD HW SATA II RAID0 (about 750 MB/s performance), CentOS 6.4, kernel 3.11.1, nginx,hiawatha,apache server limits removed:
Apache 2.2.25
Requests per second: 354.86 [#/sec] (mean)
lighttpd/1.4.32
Requests per second: 7567.74 [#/sec] (mean)
nginx/1.5.6
Requests per second: 7204.38 [#/sec] (mean)
Hiawatha
Requests per second: 521.57 [#/sec] (mean)
lighttpdproxy
Requests per second: 9573.32 [#/sec] (mean)
nginxproxy
Requests per second: 4654.86 [#/sec] (mean)
hiawathaproxy
Requests per second: 453.64 [#/sec] (mean)