Well, let's see:
OS: FreeBSD 4.11 , LiteSpeed 2.0.4
Tool: the Internet. This WAS a real world test.
Content: 85% dynamic (generated by the content servers). LiteSpeed is proxying the content servers.
Concurent users: I lost that. There where about 80 req/sec and 1500 connections on port 80 at the time. It starts happening when the traffic grows above 2.7 Mbit ( or maybe it's connection related). I initialy suspected that the 300 connection limit in "Standard" edition may have something to do with it. Just before I stopped the test the content servers logs show increased number of connections - like the proxy (LiteSpeed) would slow down and not accept the output as fast. BTW, the buffer in LiteSpeed was set to 20MB - more than enough.
I wish I can send you the log, but the test ended and the logs where minimal (high bandwidth site). I'm not sure I'll try that again, but if I do I'd like to have minimal restrictions from the software. I'm not sure it's possible to have detailed logs at the traffic we're running here.