What makes the Prime so fast?

[David]

The HP Prime has amazing modern design/hardware, super thin, solid build quality, a very impressive graphing calculator. It seems to have good battery life, moderate to minimal usage, still 100% after a few weeks (I know the gauge probably goes by 25% increments). I'm no expert, but I feel the CAS is closest to a full PC implementation and seems more powerful than Nspire CAS.
We're probably spoiled, but I'll just mention a couple of possible areas of improvement for what it's worth.
1) Although I've come to appreciate the UI's clarity and ease of use, it seems to lack the kind of top notch graphics design (fonts, GUI elements) that seems to be in the Nspire.
2) I would have preferred that the HP Prime evolved from the HP48/49/50 OS rather than the HP 38/39/40. However, HP did an excellent job incorporating all the useful features in the HP50g like the EQW, a concise RPN entry method, and all the feature rich math apps that incorporated what would have been different environments and input forms in the HP50. Also, for me there's something good to be said about the HP Prime's UI improvements when after using the Prime for a while, going back to the HP50 for me seems a bit clunky (Not criticizing the HP50) because the HP Prime seems more organized.
Just my two cents.