I obsessively measure wakeups/s in powertop for every application I use, and the above setup is very good.
If you want to try other things you can look into the mutt-kz fork (which replaces internal search commands with notmuch).
There is also a notmuch curses client, but I find mutt+notmuch superior.
Mu is a notmuch alternative worth considering. Their emacs client is excellent.
Finally, also if you use emacs, gnus is perhaps the most powerful email client ever. Steep learning curve, though. It's a bit different to everything else, as gnus has been built as a news reader. It treats mail as news, but this has some great advantages I think, as long as you can adapt your mindset. Also Org integration.
Gnus is the only thing that might make me switch away from mutt.