I've been having this same issue since about September.
I've tried shutting down Webroot too and it didn't fix it.
If I open TM and have a browser open (Chrome or Firefox) it slows down like everyone's saying. 50% of the time I have to force it shut down. If I can navigate my mouse to the close button I can shut it down. This takes about 10 minutes.
Help!
Edit: I'm using Windows 10 and it's updated 100%. I have a powerful laptop that I use for AutoCAD.
If you have not read about the workaround (not fix) of going to the Webroot Identity Protection module / Application Protection tab and checking "Allow" instead of "Protect" on Firefox, you need to try it. My recent experience was that Webroot reset me to "Protect" after Firefox updated to v58 and then again on the update to 58.0.1. I think after doing this, you then need to shut down Webroot and then re-enable it. Maybe even reboot. You should look at what else is "Protected" in the Identity Protection module - you may need to "Allow" other programs as well.
I saw that but unfortunately, this is a company PC and I do not have access to change settings in Webroot.