What is your browser doing?

Why is your browser using 50 to 100% of a cpu? When nothing needs to be done.
Why are you accessing my GPU? and starting my fans! When nothing needs to be done.
Why is it even running anything once the pages have been rendered?

I have enjoyed the browser for one year and have recommended it many time, now I am considering removing it as it starts to look like the next internet explorer doing things not asked to do.