Until Safari has support for something as simple as adding www. and .com it can render pages as fast as it likes.
Safari might load faster, but overall it makes surfing slower because its just such a pain to use.
No it goes to some other site first which corrects your error for you. I've had issues with Safari in the past where it simply went to the address without the www. and .com and because those sites had not registered for common misspellings it didn't take me where I wanted.
Try typing mplex without the www and .com and see if it works for you. Currently I am using OpenDNS which seems to correct errors for me.
well, not really, safari does add www. and .com around the string you typed.
However, I agree with your point, using safari overall slow down thr surfing experience because many usability features make firefox faster to reach the website users want to go. Awesomebar is a big example.
The problem with safari's urlbar, as your question touched, is exactly that, safari only does www. and .com, nothing else. Which is quite dumb. e.g., you type in a term with domain suffix other than ".com", safari won't go there; you type a term that has not been registered with a .com suffix, safari returns error; you type two terms, safari just plays dumb again.
I think after 2 hr use, most users will save 100x-1,000x more time than whatever safari has in js advantages, which is in the range of 0.001-0.01ms.