We've been using Jenkins for a long time on the XWiki project. It's available at http://ci.xwiki.org.

However we've been having speed issues for several years now. We've regularly updated the jenkins version we use in the hope that it would get fixed but it seems it doesn't improve much.

Right now I've noticed that if http://ci.xwiki.org hasn't been accessed for some time (a few minutes), it loads very slow (this page points to the dashboard plugin view). By very slow I mean several minutes.

I'm attaching a thread dump I've just taken now.

Thanks a lot for looking into this!