I don't know how long you have been a Chrome user, but Firefox has felt snappy and responsive for a few months now. Australis re-design shows that often speed is more a matter of impression than benchmark results.
You're absolutely right that perception of speed is largely about experience. The animations are smooth, it doesn't jump around. But I can tell that the boot times are much faster now as well.
Both teams have done an excellent job. Seeing this release has encouraged me to finally donate to Mozilla. They do a lot of good for the web.