As a general rule of thumb you should use as little JavaScript as possible and serve it in one big file. Just yesterday a client was wondering why his website was slow and their webdesigners said it needed 'more varnish cache' and a bigger server.

After inspecting I saw over 100 .js files were being requested by require.js, but because each module required yet another set of .js files and those files required another set, and so on. The server was serving them up plenty fast (<50ms) but because they were being loaded in waves the load time ended up being between 5 and 7 seconds.

Many of these issues arise from being fancy and people tend to want to fix it with fancy stuff. But sometimes you need to stop being fancy and just fix the damn problem in an old fashioned way (concatenate, minify, allow local caching).