Can't answer about copy/paste an NeoVim, but I just switched from vim -> neovim this week, and do feel it's a bit snappier. I also switched from syntastic to ALE for syntax checking and that made a huge difference as well.
For copy/paste in the terminal and vim, I usually have vim in a tmux session, and that has a few helpers to work with system clipboards. Not perfect, but better than vanilla vim's copy/paste.