> 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.

> first thoughts would be to compact your folders and if that doesn't help, vacuum the sqlite files.

Might also recommend a disk check, perhaps FS needs fixing.

At one point I cleared out all TB folders and started from scratch, problem reappeared, so I don't think that's it. Very strange indeed.

The items mentioned above should be done periodically, not just once. Perhaps there are some giant files in there too?

> The items mentioned above should be done periodically, not just once

While helpful advice - if you need to do this manual maintenance regularly, the application is broken.

Possibly, hard to know over this medium. I’ve never encountered the problem, but added the tasks to my cleanup command.

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...)

Sure. My cleanup script however does multiple things, tbird maintenance is only a tiny part.

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 have ~1 million emails in Thunderbird. The GUI thread often gets blocked waiting while it's trying to open messages. Search is horrifically slow. This is on a fairly decent ThinkPad X1.

One day I'll finally take the plunge and jump to notmuch, which I've been told is the only email client actually capable of handling millions of emails without sucking.

Quiet often it's add-ons that are are at fault, e.g. the Lighnting calendar add-on can significantly extend launch time. Starting TB in safe mode will reveal if this is the case.

perhaps put your hardware and some benchmark numbers so people can compare? if something takes 2 seconds, you might consider that "fast" and others "slow". loads of things i think are slow i realize others don't notice (or care).

Apparently load time is 1.5-2 seconds. I swear it often feels slower than that. shrugs That's not bad.

The rendering corruption/lag issue with scrolling only happens while scrolling a message while in split-pane view, not when the message is maximized in its own tab.

Its search is excellent, but the load time of the program itself, of emails, is very slow for me, on both Windows and Linux. Then the rendering! As I scroll an email it struggles to render the content and lags behind. Same problems on release, beta, and nightly. Hmm.

It happpens under various circumstances, nothing easy to pin-point here.

Example: on two identical iMacs (4 cores, 16GB RAM, PCIe SSD) with about 100GB of local synced IMAP and the same accounts, it's slow for one user's iMac but fast on the other. Deleted TB and profile, fresh user, fresh TB install, fresh config; same result.