/dev/null is your friend.
This screenshot captures part of my .procmailrc file showing how I send spam and other unwanted email to the bit bucket. The .procmailrc file is in the right pane of the Terminator window; the left pane is my Mutt inbox. (The music player is qmmp, currently streaming KCEA.)
All the “From” addresses listed in the right pane go to /dev/null, and that’s a small portion of those so designated. Since I refined my .procmailrc file to filter the junk before it lands in Maildir, Mutt has been ever so much more responsive.
The window manager is, natch, Fluxbox.
Oh, yeah. You can’t do this on Windows.