There are some universities that require you only to pass exams, and don't check attendance. You'd still need to "wait" for 3+ years. I've never seen such a course myself, only heard some stories, so it may be an urban myth.

There definitely are universities that allow taking courses at your own pace. I'm currently doing Bachelor of CS at University of Wroclaw, designed as 3.5 year course, and there are people finishing it in 2.5 years (though that's rare, it's much more usual to see 3.5 years turning out not to be enough time). Sadly, offered only in Polish, and requires a lot of time and effort.

Not the same, but I'm sure some (10?) years ago I saw something about University of Buckingham doign straight through the summer learning, so you completed in 2 years. So it isn't unheard of for everything not to be the standard 3...