BrowserSync extremely slow on OS X?
If you're developing on OS X and experiencing BrowserSync to be very slow there’s a good chance that changing the .local domain in your url to .dev will fix the problem. Why? I have no idea. The fix is really illogical but hey, it works! It might have something to do with Bonjour using the .local domain as well.
In my case I changed
http://wordpress.dev:8080 et voilà, everything’s snappy again.