Is the web browser performance rule “only 2 requests in parallel per hostname” still correct?

Question

In his book \"High Performance Websites\" Steve Souders wrote (2007) that browsers limit parallel requests to a domain/hostname to two at a time. Is this still valid today?<

Answer 1

Firefox bumped up its maximum per-server connection count from 8 to 15 for Firefox 3 and later. The maximum is less for servers that support persistent connections:

• Firefox 2: 2
• Firefox 3: 6
• Opera 9.26: 4
• Safari 3.0.4: 4
• IE 7: 2
• IE 8: 6 (except on dial-up)