Sounds like you’re having issues with your websockets or system load.
Ensure your system can keep up with it’s work.
You can verify the websocket situation with looking for “longpolling” within the logfile. if this appears, you’ll need to fix this, this draws great load on your system.
Also, if websockets are no issue, wait a minute or two without refreshing to ensure that it’s not your system being under heavy load. If you have scheduler.rb running on 100%, that’s your issue.
You might want to upgrade to Zammad 3.2 because it comes with performance tweaks (see: Zammad 3.2 is available ).
Also ensure you’re overviews are not the issue here, try to keep them as simple and slim as possible - see:
https://admin-docs.zammad.org/en/latest/manage/overviews.html