This seems like it would really complicate use of a CDN given that page content is now different based on what users have cached. You could look at cookie value

This seems like it would really complicate use of a CDN given that page content is now different based on what users have cached. You could look at cookie values and still get some caching, but this would hurt your cache hit rate. It also bars you from using a lot of the cheaper CDNs which won't let you inspect the request deeply enough to efficiently cached based on the cookie. So if you can't use a CDN or your cache hit rates are much lower, you might end up with slower page loads with technique. But of course I have no data to back this up.