NoScript would work, but when you move between pages you would have to revoke the page permissions from the page (or tab) you're leaving and give permission to the page you're moving too.
Flash and Javascript don't eat many CPU cycles unless they are doing something rather intensive (like playing a movie or running an application). Stopping those in their tracks might have adverse effects to whatever is running in that window. Most well designed sites limit the Flash and Javascript usage to small portions or provide that they don't continuously run in a loop.