We just rolled out a new Zimbra Network Edition installation (50 users). We are not taking advantage of a clustered installation - all features of Zimbra are hosted on an HP DL320 G3, 3.4GHZ, 1GB RAM, 160GB HD running RHEL 4, update 2.
Everything seems to work wonderfully. Our users, after some initial Q&A, respond positvely to all aspects of Zimbra but speed of the user interface. These users are accessing Zimbra, for the most part, on our LAN (gigabit) using Firefox 18.104.22.168. We have a mix of Dell computers (all +1GHZ, +512MB) running Windows XP and Intel iMac's w/ Firefox 22.214.171.124. The most important user, our CEO, is on a Dual G5 PPC.
I'm investigating some ways to increase the speed of the Zimbra user interface. I realize we only have one HD, and that could possibly limit the speed in which we write/retrieve data. As well, only one processor (the GL320 only supports one processor). Is adding additional RAM (to total 4GB) going to maximize the user experience?
Unfairly but realistically the Zimbra interface is being compared to Horde, a popular web-based E-mail client we used to use. While I realize Zimbra offers huge benefits beyond what Horde offered, our users enjoyed the snappy response it offered.