If it is across the board, then the solution is much harder to figure out. Have you installed anything recently like a firewall, virus program, or any other software? I'd also try running IE11 and the other browsers in safe mode. Maybe you have the same extension/plugin in each browser that is somehow coming into conflict with a Facebook script. If you have Windows Vista through Win 8, just press the Start button and type "iexplore -extoff" (not quotes) into the search bar. That will launch an instance of IE11 in safemode with no add-ons. You'll know it is working in that mode because the default view actually says something to that effect. If for any reason that does the trick, then launch full IE11 and try turning off the add-ons one by one until you find the culprit.

Perhaps your ISP is throttling FB or just has poor connection to it? What happens when you use another ISP?

Strange indeed. We just happened to be staying at a Country Inn and Suites in Atlanta this weekend. I took my laptop to test this. Turns out I had no difficulty whatsoever with speed or connection at the hotel.

Even stranger... when I returned home and reconnected to my wireless system this morning, everything was back to normal working speed. It was as though there was never any speed problem.