We were able to improve buildbot performance on build.chromium.org by making a change to a heavily hit LRU cache. We're still working on getting the change upstreamed, but build.webkit.org might be interested in cherry picking the patch rather than updating buildbot. The upstream issue is: http://trac.buildbot.net/ticket/2246 And the patch and diff are here: http://codereview.chromium.org/9703108/
szager@chromium.org can provide actual numbers on how much it helped on build.chromium.org, I'm just relaying the message.