Replace buggy Message Center widget at geocaching.com with modified local version.
This experimental Browser add-on prevents message-center-header-widget.js to load into cache pages and map. I hope that this resolves freezing problems experienced by many Firefox and Chrome users, until the problem is solved by Groundspeak®.
When this add-on is running, the number of incoming messages will be updated only once and displayed in black colour. Message Center itself and some other pages does not use this widget, so there you will see ordinary white numbers updated in real time.