Update Jun 26, 2015
My entire server setup has changed (once again). I now have the ripper running on real server hardware, (named amarok). That means that we have gone from a dual-core pentium to a pair of quad-core Xeons working in tandem with 2.5x the RAM. That oughta speed it up!
(All other servers are not currently able to rip for various reasons. The rebuilt ripper I promised is still under way, but it got delayed due to having some sort of life outside a terminal shell.)