This is getting more and more complicated. Can #webperf community help me? What is the best way to figure out a slow network? Some time ago it was Save-Data header and now we got ECT and Downlink network hints. Save-Data seems not getting rather popular looking at Web Almanac. Using the other two with CDN (cache key) would be a "fun" exercise and needs a server side opt-in. The problem I'd like to solve is to serve lower-quality images to users with slow networks but have a good CDN cache hit ratio at the same time. @simon @tammy @Yoav @anniesullie