Dolphin is approximately as fast as mc for me at listing large directories, both the same speed as 'ls'. Which is quite impressive when you consider how much more metadata it will show than mc and that it has a full graphical widget displaying them with thumbnail previews. AFAIK mc can't even show mimetypes in the file list, but Dolphin will load them asynchronously after listing the directory as you scroll.

Ranger is pretty nice to work with as far as TUIs are concerned -- bulk rename, N-split panes, tabs, image previews... it does a lot, and the default view is surprisingly usable to look for a file.

The only thing I miss with it is a "goto" shortcut, à la vim sneak. Ironically, Dolphin or Explorer go to a file when you start typing its name. Don't get me started on GNOME searching files.