DISQUS

If you want to test your system with a really large data set (150M triples), have a look at http://www.isb-sib.ch/~ejain/rdf/data/ :-)

I believe the only way to load such amounts of data within reasonable time on reasonable hardware is to make use of the underlying database's bulk loading facilities - I gather you chose a similar approach. We can load 6'000 triples per second, most of which is required for building all the indexes...