Real-time gets stuck

Real-time widget gets stuck and stops showing new visits, and would like to know what setting is most vulnerable to it getting stuck like this? My server is very fast and reliable so that cannot be it. The refresh rate is at 5 seconds if that plays a role, but I tend to doubt it. When I refresh the dashboard, it shows those missed. Everyone is captured in my visitor log, just the real-time widget freezes… Which setting can I loosen, or is there such setting, Basically, what are the things I need to check in order of most probable culprit?

I do get heavy traffic, about 100-500+ visits a minute…

Bernard St-Pierre
Marketing Consultant

Maybe the SQL query is timing out… Can you run a SHOW FULL PROCESSLIST; query in mysql when the real time query is not coming back?