A second is a lot of time to play some notes in. I hit ten notes per second a while ago (not very fast compared to many others) and its really not very impressive. If you have the right mindset, I dont think it would be that hard to play 30 notes per second. I just havent been playing long enough to do it.
And whoever said that thing about Vai not being the fastest and all that and the stuff about the 16 year old. I think that 46 notes per second is very impressive, and I would never be able to play that fast, but such playing, to me, is very harsh and unmelodic. The speed most shredders play at (20-30nps) is a good speed to play at. But then you get people like Yngwie who do it through an entire solo and that gets just as tireing.