Hi,

"Large" in the context of this issue is >20 replies, I have to wait ~1 sec until the thread shows up. With larger conversations it get's worse (a bug report on bugs.kde.org with ~400 replies takes ~13 secs. to load).
This is due to the fact, that notmuch-{vim,emacs} load the complete mail including the body.
ner does a great job here, it loads all headers but only the body of the first unread mail, resulting in instant loading even of gigantic conversations. It would be terrific to see something like that, at least in my favored vim-client ;)

Thx
Franz