tl;dr Your browser is getting slower because some repulsive companies just can't keep it to themselves. The level of sophistication is far from trivial, linked

tl;dr Your browser is getting slower because some repulsive companies just can't keep it to themselves. The level of sophistication is far from trivial, linked from the article: https://webkit.org/blog/8146/protecting-against-hsts-abuse/ https://webkit.org/blog/8146/protecting-against-hsts-abuse/ "An attacker seeking to track site visitors can take advantage of the user’s HSTS cache to store one bit of information on that user’s device. For example, “load this domain with HTTPS” could represent a 1, while no entry in the HSTS cache would represent a 0. By registering some large number of domains (e.g., 32 or more), and forcing resource loads from a controlled subset of those domains, they can create a large enough vector of bits to uniquely represent each site visitor."