Port range is net.ipv4.ip_local_port_range = 32768 61000, so I guess that's pretty standard and shouldn't be a problem for this benchmarks (which involves at most 500 requests).

I've tw_reuse and tw_recycle, but that does not seem to be having much of an effect.

In rough numbers, what's the expected per-core throughput of nginx in reverse proxy mode? (with or without gzip'ing)