Do you get a 'Not responding' message in the title bar?

I have this problem, too. I'm on a Mac, using T'bird 52.5. For several minutes, it says Loading Message... -- I finally wander off to do something else, so I don't know how long it actually takes. It's painful. And to be honest, it comes and goes. A speed test shows our internet speed is A-OK. I would be happy to pay for customer service -- if there were such. I do not get a "Not responding" message. TIA for help from anyone.

EllenBl,

please start a new topic for your problem. https://support.mozilla.org/questions/new