I recently migrated my 7.x Zimbra installation to 8.0.3 running in a CentOS 6.4 x64 Virtualbox VM. Everything is running fine, but for some reason after hitting "Send" on any new messages, it takes around 20-30 seconds for the task to complete when prior to the move/migration, it was near instant.

Any suggestions as to where I might begin looking for the source of the problem/delay?