I tried the game in Firefox and Google Chrome, and it did not execute a single command when I pressed STEP or RUN.
Memory does not change, neither does program pointer wander.
As for scrollbars - chrome fix is not difficult but every other browser sucks; I dislike js solutions for this issue :/ I need to consider hiding them entirely maybe, not sure yet.
The first button in editor panel ([ ]) toggles fast mode ([ ]/[F]). I'll add super fast. Not as fast as you wish I guess though. Need to optimise drawing code first; I guess it'll be super-super fast in the future :)