While looking at the performance graphs for the single-record select test during the last year - http://home.online.no/~olmsan/derby/perf/select_1y.html - I noticed that there was a significant increase (10-20%) in CPU usage per transaction on the client early in October 2010. To be precise, the increase seems to have happened between revision 1004381 and revision 1004794. In that period, there were three commits: two related to
DERBY-4757, and one related to DERBY-4825 (tests only).
We should try to find out what's causing the increased CPU usage and see if there's some way to reduce it.