I can confirm that an i5-4200U (decent < 1000$ notebook) goes from 2-4% lowest proc frequency to 14% max proc frequency (and the fan starts). Using Firefox. It

I can confirm that an i5-4200U (decent < 1000$ notebook) goes from 2-4% lowest proc frequency to 14% max proc frequency (and the fan starts). Using Firefox. It is clearly noticeable. Of course YMMV