"DNS cannot be parallelized with HTTP" I meant that DNS requests are parallelized within the browser. Once it loads the initial resource (html), there might be

"DNS cannot be parallelized with HTTP" I meant that DNS requests are parallelized within the browser. Once it loads the initial resource (html), there might be 10 more dependencies it needs at various different URLs under different domain names. It's usually loading all these dependencies that make up the vast majority of the load time on a complex web page. Those subsequent DNS requests can of course be made in parallel, so if your DNS latency is 20ms then you're adding ~20ms, not 10 x 20ms. Even then, DNS is probably making up a small fraction of the overall load time. If a complex page is taking, say, 3000ms to load and render, then adding 20-40ms of DNS time is not going to make a perceptible difference.