Why is Flash so hard on the CPU?

Question

Recently I hear Steve Jobs citing this as a main reason to not have Flash on IPADS

Answer 1

I would say that the main reason is doing animation and other graphic calculations, like alpha compositing, graphical filters and such, using the CPU instead of the GPU. Flash applications that don't animate are not very heavy on the CPU.

The same thing can be seen in many of the HTML5/canvas demos of late, like http://9elements.com/io/projects/html5/canvas/ or animation intensive stuff at http://www.chromeexperiments.com/ that are very hard on the CPU. So I would say it is not Flash Player as such that is heavy on the CPU, it's the stuff that Flash is often used for that is.

As for the reasons why Flash is not on iPads, I can of course only speculate, but one thing people tend to forget is that no browser plug-ins are allowed on the iPhone/iPad. So stuff like Unity and Silverlight is also out, not only Flash. Java is not on there either.