I've had no problem with previous versions of Firefox. Since installing version 63.0.3, constant problems with crashing, hanging or loading homepage and websites extremely slowly. Sometimes loading of homepage cycles through two or three partial sequences before completing. Have tried all obvious recommended solutions without success, including safe mode, refresh and reinstall. Am using MacBook Pro 10.10.5 and BT as my home page. I use Safari as my other browser and it continues to run without any issues