As some people have noticed Zimbra 6 consumes a lot more load (link) than Zimbra 5. The entry is well described, and I can just concur this with my own installation:

<-- why don't I get an image in the forum? :/ Anyhow, click link to reveal.

Upgrade in September.

I use Zimbra OSS for home as it offer a great suite. It is a single server deployment. Currently running in a virtual host with 2GB RAM and 3x 2.4GHz CPUs for disposal, as I had to increase from 1 to cope with the load to get some reasonable response time (w-t-f )

As another writer (link) clearly gets a response to is that a downgrade is not supported.

I would probably just restore the obvious backup that I made before upgrading, but I hate the thought of losing several months worth of mails due to this.

Is someone working addressing this issue?

Can I downgrade?

If not, can someone point me out how I can make a new fresh installation and migrate my mails, settings and accounts to the older Zimbra?

Any advice would be appreciated.