[drdaeman]

It always was slow with larger mailboxes, taking a few seconds to react to a click (and sometimes freezing for minutes to move a bunch of emails ti a different folder).

I can’t tell if it’s any slower with Supernova or not. Feels about the same, to be honest. I suspect its bottlenecks are somewhere else.

[jeltz]

On my computer it is much slower now. It was always slow on large mailboxes but now it is almost unusable and I am thinking about downgrading or switching. Any recommendations?

[littlestymaar]

Are you using POP3 or IMAP? In my experience thunderbird on IMAP has always been very slow whereas I have no problem on my 2012 laptop with 30k emails when using POP3.

[jeltz]

I use IMAP and, yes, it has always been slow but something also happened with the new UI.

[mixmastamyk]

Compact the folders. Vacuum the sqlites. Also could move old mail to its own folders.

I have mail back to the mid-nineties and it works fine, besides a few UI glitches from the new version. (There are buttons that can't be removed.)

[jeltz]

I do that from time to time. The issue is that the performance got worse with the new UI and that cannot be due to compacting. Will try to do it again though to see how much it helps.

[mixmastamyk]

My laptop is 5+ years old, and while TB is not the snappiest GUI app on the machine, performance is decent/acceptable. I welcome any optimization however.

The vacuuming is important on an older install I suspect.