Another approach to spreading Zope resources across multiple machines is to divide entire high level folders (branches) so that each has a dedicated processor, RAM, etc. Then only the "topmost" common folder(s) need to be replicated. Of course you'll need to come up with an effective means of testing on a development system, and syncing after updates. No, it's not as clean as ZEO or a shared data.fs, but it may help solve the load problem, for awhile at least.