I’ve had to stop using tmux on macOS (MacBook Pro 2018).
For some reason I kept getting extreme slowdowns/laggy behaviour when using neovim.
I’ve seen this thread: https://github.com/tmux/tmux/issues/353
I tried everything in the thread and still end up with a laggy terminal. For now I just use iterm2 with tabs but I miss my tmux.
On my personal Linux laptop, I never encounter the same lag with the same setup.