Lucene performance tips for 64 bit machines
There has been an interesting discussion on the Lucene mailing list on how to get the most performance out of a 64 bit machine. See here
for a full discussion.
There are some different Directory implementations one can use that should reduce synchronization and improve IO.
Bottom line: Make sure you are using a 64 bit JVM!
Of course, I wish I had the problem of figuring out how to get an 8 CPU box to run really fast!