I've just started using Portable Thunderbird and things are going fairly well.
It's a little slower than I'd like, but that could be just the old drive I'm using for the time being.
One thing that isn't working is the notification that Thunderbird puts next to folders that have new items within. In 'Desktop Thunderbird' the little satellite dish is highlighted with an orange star whenever there are new unread items within a folder. In Pocket Tbird, the change only happens once I click on a folder. That is, I get the 'highlighted' state, but only after clicking the folder, which otherwise looks like all the others.
Is there some setting that controls or can fix this?
Thunderbird Portable (note - not pocket) and Thunderbird are the same program. There is no difference in them at all.
If you're getting different behaviour from the two then you've either got different settings or you have an extension on one and not the other.
I switched to another USB drive and Tbird now works much better. I think the other drive was just too slow to keep up.