@eyoungren - thanks so much for this recommendation. After Firefox locked up my MBP for the umpteenth time last night, I installed Vivaldi and made the switch and not only have my problems vanished but I've also witnessed a drastic increase in functionality. Previously I was dependent on using two browsers simultaneously but neither of them met my needs adequately. Vivaldi fulfils this role and more - within just one program.
I was able to import my bookmarks and browser history from Firefox quickly and easily. My passwords required a bit more work with the help of the freeware
FF Password Exporter which created a .CSV file that Vivaldi could then import
via the following steps:
It wasn't even necessary to restart the browser, it was possible to log into the respective sites immediately. How's that for efficiency?
I also disabled the internal adblocker and anti-tracking facilities and installed uBlock Origin instead which is far more effective.
All of my favourite extensions have Chrome versions so that was great - as was the fact that I didn't need to spend time working around configuration bugs that haven't been corrected despite them being highlighted for years as problems - which was the case with Firefox involving the most of simplest of issues.
Thanks again.