Human Brain
"You brain does it in 20 watts, but it will think many orders of magnitude slower"
Differents parts of the brain works at different clocks speeds. In fact the brain is like a multi core CPU, each core being specialized and working at a speed adequate to its task.
For example the first time you type on a keyboard, you do it with your "intellectual core", thinking about your moves and searching for the letters, slowly typing. Later, your "physical movement core" knows how to type, and you no longer bother on how to do it. You do it faster, and your "intellectual core' is free for formulating the phases that you type on the keyboard magnitudes faster.
It would be fascinating to benchmark the diffrent areas of this incredibly powerful computer, the human brain.