A common trick I use with client work to speed up asset delivery is use cloudfront as an asset host. I'm surprised this technique isn't in more widespread use as it reliably makes for snappier user experiences, especially users with a fresh cache.

This guide assumes you're using the Rails asset pipeline to package and serve your assets. If you're not using the asset pipeline, whatever solution you use to achieve the same result will need to fingerprint asset filenames with some sort of unique identifier for it to work smoothly with Cloudfront or a CDN like it.