We have a Zimbra ZCS 5.0.11 Network Edition running on Ubuntu 6.06LTS configured as single-server environment, but as it doesn't perform at all I'm thinking about moving to a multi-server environment having the mailbox part running on its own server. But I haven't been able to find some good guidelines on this process.

Does anybody know the best and fastest way of performing such a migration? I'd prefer migrating to new servers as I can preserve my existing setup if the migration doesn't work properly.