Today a quick jump to an issue that can cause a considerable delay:
When a user has no linked folders, logging in to Zimbra will be a pleasure.
In contrast to this, the login can slow down to a minute or so if folders from other workspaces, some of them with deep hierarchies, are linked.
I guess that Zimbra is programmed in a way that the whole folder tree is walked down for proper display before the inbox is displayed to the user logging in.
We think that it would suffice if that folder cache is filled later on, when actually needed. This would spare the affected users a long waiting time.
There is an enhancement request addressing this:
ER 10639041: [ER] ZIMBRA: LINKED FOLDERS WILL SLOW DOWN THE LOGIN CONSIDERABLY
Please second this enhancement request through MOS to further its timely implementation: it is said to be investigated for implementation in 188.8.131.52