> This is a frequently heard complaint, but I can't imagine under what circumstances this would happen.
I see it both fast and slow. Ironically it's absurdly slow on my 8-core desktop and just fine on my older dual core laptop (both with SSDs and same accounts, etc). Definitely weird, but this behaviour has peristed for years, so much that I had to disable TB features on my desktop just so I could type without stalling.
Not to denigrate the hard work of developers (particularly open source developers) who work on very complex application software like Thunderbird, but software designed for regular users needs to cope without cleanup scripts. (Yes, yes, I know that reinstalling Windows from scratch is a time honoured tradition...)
Maybe the old folders used mbox, which stuffs entire folders of emails in a single file, while the current stardard (for a while now) is Maildir, a file per email.
I see it both fast and slow. Ironically it's absurdly slow on my 8-core desktop and just fine on my older dual core laptop (both with SSDs and same accounts, etc). Definitely weird, but this behaviour has peristed for years, so much that I had to disable TB features on my desktop just so I could type without stalling.