I did give emacs --daemon a try, and that definitely helped with the long startup time. I went so far as to alias vim to emacsclient -t. But what I mean when I say it was laggy is that typing and cursor movement are ever so slightly less responsive. Not MS Word on Windows 3.0 laggy, just enough for me to notice the difference. I dug into it a little bit with spacemacs and vim open side by side, and according to top, spacemacs was using about 10x the CPU of vim.