If you use the W3 Total Cache plug-in -- which is a great plug-in -- DO NOT UPDATE TO WORDPRESS 4.7 WITH THE PLUG-IN ENABLED.
It took my admin area (at RRND) down completely. Fortunately, Hostgator support was able to get my ass out of the sling it was in. I've effused about Hostgator before. If you need hosting, I highly recommend them, and no, I'm not recommending them on commission or for any inducement. They just rock, that's all.
Update, a few minutes later: My experience and other people's recommendations is that W3 Total Cache is a great plug-in. But as of a few minutes ago it was indeed labeled "untested with your version of Wordpress," so I expect there are some incompatibilities and that W3 will get things fixed ASAP. Until then, I'm using a plug-in called Comet Cache which HAS been tested with Wordpress 4.7 and DOESN'T break my site (I assume it works, too, guess we'll see).