How powerful is the computer in NASA's New Horizons spacecraft?

The biggest news in the solar system yesterday was NASA's New Horizons probe. After a journey spanning three billion miles over nine and a half years, the spacecraft arrived at its destination, Pluto, and sent its signal back to Earth.

Following the event, a group of NASA scientists from the project took to the social media site Reddit to answer questions from the Internet audience. One question that stood out to me came from a user called bambiwoods, who asked,

How powerful is the computer inside the spacecraft?

NASA Program Scientist Curt Niebur answered:

The computer is a whopping 12 MHz. Yes, you read that correctly: 12 megahertz. People are always surprised at how much less powerful our flight computers are compared to their home computers. But we build them rugged. If you bolted your laptop atop a rocket, violently shook it, exposed it to vacuum, and had it endure temperature extremes and radiation, then your vacation pictures might be at risk. But ours will be just fine.

Really makes you appreciate the Intel i5 processor in a Toughbook 31.