|Autocomplete prefetching over the network before I hit enter.|
There's nothing like proper optimization, done in small steps, when needed. On the other side of the coin is premature optimization which is the bane of any software engineer's existence. (Rules to Code By)
Another Safari optimization trick I read about but haven't confirmed is that, after loading a web page, Safari will prefetch each link's IP address for faster loading when a user clicks on it since the DNS lookup has already been done.
Anything to speed up my Internet experience is OK by me.