Looks like you missed this thread... BIS Outage 02/20
If you're experiencing long delays outside of today's outage... then you might want to check the following:
Stability of your mail server(s) that you're retrieving messages from.
Quality of data coverage on the areas your are frequently in.
If "immediate" message delivery is critical for your work, then you should be looking at a BES solution... not BIS.