The major issue with opera is that you can't easily automate the tests, that's why it's often missing when people test IE and Chrome and FF.
So it's hard to benchmark stuff and most don't take the time to do it.
sort of, a lot of the actions by this script rely on the browser giving feedback (e.g. finished loading the page). You could write a script to gather feedback from the display (i.e. by taking screenshots) but it's too much effort to maintain with new releases.
That said opera is known to be rather fast.