Maximum Possible Insert Performance?

My situation is this. We have a semi-production server where we
pre-process data and then upload the finished data to our production
servers. We need the fastest possible write performance. Having the DB
go corrupt due to power loss/OS crash is acceptable because we can
always restore from last night and re-run everything that was done since
then.

I already have fsync off. Short of buying more hardware -- which I will
probably do anyways once I figure out whether I need more CPU, memory or
disk -- what else can I do to max out the speed? Operation mix is about
50% select, 40% insert, 10% update.