Google+ Messenger conversations are supposed to take place in real time. Yet when I use Messenger with the Google+ app for my Nexus S Android 2.3.6 phone via 3G (Vodafone IT), the messages I send or receive from others are often delivered with delays ranging from a few tens of minutes to a few hours.
Does Messenger require push notifications, i.e. setting the Settings -> Accounts & sync settings -> Background data checkbox?