Has any work been done on identifying the browsers connection speed so that we may serve high quality vs. low quality assets? The only thing I've been able to f

Has any work been done on identifying the browsers connection speed so that we may serve high quality vs. low quality assets? The only thing I've been able to find for this is the MaxMind GeoIP Netspeed database, but I have no idea if the data is accurate enough to be valuable. I suppose you could measure latency, but not during the initial page load..