[webwanderings]

I recently downloaded TB to move some offline mbox emails of large quantity. TB became increasingly slow processing few thousand. I downloaded Opera Mail to do the same exact work. I was done within few hours.

I have a need for more people to repeat the same process. There's zero chance I'll be asking them to download TB.

[cat199]

TB by default saves 1x file per folder (e.g. MBox like) -

This means depending on your storage configuration and how you use folders, potentially writing 100MB, 1G, 10G, etc. back to disk on folder content change.

For batch processing though, I use the CLI tools - thunderbird is view/compose only (procmail/formail/archivemail/offlineimap,etc)

I was hitting performance probs on bigger folders, and setup some more strict archiving to archive older mails to subfolders/zap offline using an 'archivemail' job, etc, and the problem went away, with TB being quite snappy.

as I understand it there was some effort to support 1-file-per-email, which might be an option now, but this has it's problems too.

Outlook has it's PST corruption hell...

Basically, in my opinion, email is a pain, each client shows it differently, though I am admittedly not up to speed on Opera Mail.

[jacquesm]

Thunderbird sets up a full-text index to allow you to search your emails. This eats up a bit of time while importing large mailboxes but is quite handy once it is done.

[webwanderings]

I tried that (I googled to see what am I missing) didn't help.