I was just talking this week to one of the guys on the original chrome team. He told me in the beginning they were obsessed with speed -- there was a benchmark in place for time to load from cold boot that wasn't allowed to go up (80ms). So if you wanted to do a new feature you had to jump through hoops to make sure it didn't slow anything down.

Eventually chrome became mainstream, Google started advertising it on their homepage, and features started becoming a priority over speed. At some point the benchmark test case for load time broke and no one fixed it, and things started to slide.

I'm hoping servo provides the necessary investment and juice to restore Firefox to a good browser again (after many, many years).