Calendar not refreshing

Any ideas why the calendar often doesn't refresh properly any more? I've had several people report this. For me it happens consistently with Firefox, but for others with IE 11. Haven't heard of any problems with Chrome. No amount of changing calendars or views or logging out and back in seems to help, but rather just a general manual page refresh.

My guess is that there is something about the way the page loads. The server and computer think they have completed the display, but they have not.

I have seen this at other sites, as well, where it takes so long to load the page from the server that the computer finally stops asking for the rest of it. The refresh loads more quickly because page elements are already there. So the refreshed page also loads more completely.

As to who needs to recode what, however, I would be at a loss. I am merely able to tell what I see happening, or not.