Note that JBC3 only supports REPEATABLE_READ and READ_COMMITTED. So your READ_UNCOMMITTED setting effectively gets upgraded to READ_COMMITTED. What's the purpose of setting your eviction wakeup interval to 0? You realise that the eviction thread will not run with such a setting, so your eviction settings after that are pointless. Finally, in your test, is this run with a single thread? Do you have anything else happening at the same time, e.g., writers? Have you tried profiling this? If you don't have any other concurrent activity, especially writes, the spikes you see could be GC spikes, as it does seem to be pretty regular. What memory settings have you configured your VM with? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4195915#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...