gnome max-out during sign-in in Firefox.

(f29; gnome; Firefox 68.0; all patched late this morning) While trying to sign on to a financial institution's web site, when I start to enter the password, the cpu suddenly gets extremely busy and stays that way. I had to hit the power button. Upon booting up again, I launched ksysguard, and then re-tried the login. Again I saw the cpu essentially max out. I had to hit the power button. Upon booting up, I launched "top" in a terminal, and then retried the login. Again the cpu essentially maxed out. "top" showed that gnome was the cpu hog. I again hit the power button and booted up. This time I logged in to a plasma session. I was able to log in and do what I had to do with no problems. This one is really strange. How do I determine what the problem is? This problem did not occur before today's "dnf upgrade". The last patching before today was last Thursday. thanks, Bill.