Yes. Browsers and protocols have changed, and a lot of past performance best-practices have become actively harmful for performance. A couple of related techni

Yes. Browsers and protocols have changed, and a lot of past performance best-practices have become actively harmful for performance. A couple of related techniques are also useless: domain sharding and cookieless domains. HTTP/2 multiplexing and header compression made them obsolete, and now they're just an overhead for DNS+TLS, and often break HTTP/2 prioritization. You should be careful with prefetch too. Thanks to preload scanners and HTTP/2 prioritization there are few situations where it is really beneficial. But there are many ways to screw it up and cause unnecessary or double downloads.