The performance lag of Spacemacs was addressed by Doom Emacs ( https://github.com/hlissner/doom-emacs ). Have you tried Doom Emacs by any chance. After syncing everything, the performance is stellar in my opinion.
This collection page of Emacs packages: https://emacs.zeef.com contains only packages which are last updated at least 2 years ago, and it's already an impressive amount to me, which indicates that Emacs community is also very active, despite having - in IT terms- a very ancient editor.
I struggled a lot with my Emacs setup, and developing for clients and languages. But I was able to puzzle my pieces together with https://emacs.zeef.com , it is your friend
One of my biggest issues with terminal based file managers like Ranger or nnn (https://github.com/jarun/nnn), is that it's not immediately clear which files I'm currently looking at, since it's all text-based (duh!).
But I loved the extensibility and keyboard driven nature of the terminal-based file manager. That's something which other GUI-based filemanagers are lacking in that, except fman.
Far Manager looks interesting to me, since it seems to be allowed extensively customized too. Will give a try soon.