I haven't slept for a week..
but now it should be very easy to maintain a FreeBSD port since 99% changes are in the java stuff which is 100% portable.
I have no idea how it performs since I have never run it on Linux (nothing to compare to). I will be happy to give someone skilled access to some box so that he/she can test it.. if they have time to do it.
The usual 1minute/2minute cpu spikes are resolved via:
zmlocalconfig -e zmmtaconfig_interval=6000
zmprov mcf zimbraLogRawLifetime 7d
zmprov mcf zimbraLogSummaryLifetime 30d
and setting zmstatuslog in crontab to a higher value.
I am pretty sure that IF it performs badly someone will be able to tweak it. I am going to deploy it as a central mailer for the university so we will see soon enough :-).