Yes, I've tried many things, including a new profile. Compacting would help for a few days. Thunderbird just doesn't seem to do well with large mail archives go

Yes, I've tried many things, including a new profile. Compacting would help for a few days. Thunderbird just doesn't seem to do well with large mail archives going back more than a decade. That is my experience and the experience of others. Also, I've met many people who experience similar performance issues, so I find it bothersome that because you've never encountered it you're asserting it does not exist. This is also an issue that's span multiple machines and multiple clean installs.