Little background. I've been running Zimbra for two years now with good results. I'm running on Ubuntu 8 LTS 64-bit.
I recently upgraded from 6.0.10 to 7.1.1 (Release 7.1.1_GA_3196.UBUNTU8_64 UBUNTU8_64 FOSS edition specifically).
I've noticed that my average delay in the Message Delivery section of the Daily Mail Report has increased to 3 times what I used to see. It still isn't high, just about 3 seconds most days, although yesterday is was 8.5 seconds. The worst it ever got before was 2 seconds. I've also noticed that mail going to my local server has max delays of sometimes 15+ seconds. This always used to be sub-second.
It isn't much of an issue as the server sends/receives barely any mail. I'm more just looking for an explanation. Most people seem to be getting performance gains when going to 7.x. I'd also like to know if I messed something up with the upgrade, although, they're very straight forward, so I'm not sure how that'd be the case. I did run the separate DB update.
The box is also barely being utilized (low CPU, memory and disk utilization, like 10%).