Update 2013-02-08: I ran some tests on the above configuration with ab, but the variance was so extreme (some runs of 10k requests averaged 4k/s while others averaged 500/s) that I think something else is wrong.
Update 2013-02-08
Update 2013-02-08: I ran some tests on the above configuration with ab, but the variance was so extreme (some runs of 10k requests averaged 4k/s while others averaged 500/s) that I think something else is wrong.