Probably you know that that keeping the disk & transfer size of a JavaScript file low is pretty important. But have you considered the time needed to parse and compile the code? In this great post on Medium Addy Osmani, an engineer at Google, explains the complete cost of having JavaScript on your page.

As we build sites more heavily reliant on JavaScript, we sometimes pay for what we send down in ways that we can’t always easily see. In this post, I’ll cover why a little discipline can help if you’d like your site to load & be interactive quickly on mobile devices. tl;dr: less code = less parse/compile + less transfer + less to decompress