That’s a lot of files! If you’ve ever noticed the excessive flickering happening in your browser’s status bar when you go to Facebook, this is the cause.
How can they improve the situation? The total file size isn’t too terrible at about 100k of JS and 40k of CSS. The best thing to do would be to use a simple build script that concatenates all these files together into one larger file. If they can’t do that for some reason, they could at least serve the files from more than one domain to take advantage of parallel downloads in the browser. They could also try a service like Akamai, but that’s a bit more complex and expensive.
This seems like a really silly oversight from an organization that in general produces beautiful work. My guess is that when the company was getting started they set up a relatively simple build process that has now become ingrained and difficult to alter as their setup has quickly become larger and more distributed. However, they’ve reached the point where it’s time to revisit things and do it properly.