When I launch app, I takes up to 10 seconds to reconnect. It’s more reliable to occasionally open app and check for new messages, than to wait for notification to appear. I am in Russia, connecting to my friends in USA
Could you let me know what version of the app you are using? This can be found by navigating to the Profile tab, clicking the Gear icon and then selecting “About”. The text underneath the Battle.net icon is the version.
Connecting to the Americas region from Russia will inherently increase the amount of latency, but you should not see a delay in push notifications.