Why does Google+ Messenger deliver messages with long delays? 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 &amp; sync settings -> Background data checkbox?
Google+ Messenger does require the Background data checkbox to receive messages/updates while it's not the active app. However your messages should be sent instantly since the app would be active then.

Are you experiencing delays with other messengers using background data as well? e.g. WhatsApp

A good discussion about background data, sync etc can be read here