Server side logs and sessions. You should be able to tell users devices/browser and what bandwidth they operate. Then calculate average speed they use. You coul

Server side logs and sessions. You should be able to tell users devices/browser and what bandwidth they operate. Then calculate average speed they use. You could then create tiered service where media quality and JS features can be adjusted. You will periodically process logs to make sure that grouping is still correct. As additional feature users could choose in theirs setting what tier they want to use. On client side, You can achieve some of this by heavy use of media queries. https://msdn.microsoft.com/en-us/library/windows/apps/hh453556.aspx https://msdn.microsoft.com/en-us/library/windows/apps/hh4535... You can basically manipulate resolution/disable of assets based on screens quality. This is under assumption that someone with retina screen will have decent internet.