You do not say here which version of FF or Ubuntu or anything about your
hardware or previous history with these browsers. Nor do you say which web
pages. It makes it hard to troubleshoot. My versions of Opera DO support
multiple start pages. I do agree that Chrome is a memory hog. I have 14 web
browsers installed and all work differently. Some are good and some are not
so good. Some are very specific to certain tasks.

l> have to literally fiddle with video port on computer while
l> repeatedly restarting w/power button before it finally works.

Not good for the system having to do that and presumably once you get
it working it's OK apart from the browsers ? Usually I've found the
root cause of reluctant booting is hardware - number one suspect being
the power supply unit and I'm still coming across these with blown
capacitors though this scourge appears to have gone on motherboards !!

Are you able to fit a replacement power unit, even temporarily to
check that this fixes the reluctant boot ?