The browser I'm using at the moment is faster than the one I was using three years ago, despite also having a very large number of new abilities.

Further, a significant number of my current OS processes are currently executing programs themselves (with various degrees of dynamic compilation). I'm not clear on when it's okay for a process to itself execute a program. Is interpretation ever okay? Or does it always need to be dynamically compiled? Also, what's the rule on compilation of turing complete languages like Postscript?