There must be a formula for queries a year, returning users, versioning and caching resources. I bet inline styles and scripts are heavier in the long run than

There must be a formula for queries a year, returning users, versioning and caching resources. I bet inline styles and scripts are heavier in the long run than cached as external resources for millions of requests, specially multiple requests a day per user. Now, I don't know how cache works, but if you have to make a resource request just to get a 'has not changed' response, then the problem is in the protocol. How about sending all 'modified-since' tags in the header for every resource, so the client then requests a second bulk with all the resources required? Somebody can explain how cache works in the browser?