That's clever, but it still sounds like a way that information could be leaked. Download the target resource, and then download it again concurrently with a kn

That's clever, but it still sounds like a way that information could be leaked. Download the target resource, and then download it again concurrently with a known unique resource, and see if the timing changes, for example. It's an arms race where the browser would ultimately have to simulate every consequence of actually downloading every resource over the slowest link in the network. You're making the problem (and its solution) more complex but not completely solving it.