I eventually had to switch off Thunderbird as well for similar reasons and just live with mutt. TB just really didn't perform well at all on large mailboxes (d

I eventually had to switch off Thunderbird as well for similar reasons and just live with mutt. TB just really didn't perform well at all on large mailboxes (dozens of folders, thousands of messages per folder) without freezing the UI, gobbling gigabytes of ram, etc - it is obviously not targeted at my use case.