This is the Firfox 57.0 upgrade that has been touted as faster and more secure for some time. I upgraded to the 57 Beta several weeks ago. Can't say I've had any serious problems apart from losing an extension. A replacement was available and it is an improvement over the old one.
Can't say it's a gigantic improvement either, though security, or lack of it, is not always visible until there is an attempted hack. Most of the problems I've experienced are with misbehaving scripts and that existed previously. That's handled a little bit better in the latest version. Speed is better but it's still not as fast as Google Chrome.
Problems with icons, especially on the task bar, could be Windows related. The Win10 Creator's Update broke something there and I've noticed a few other odd things sine the CU final release.