Less speed = less heat which is surprisingly a large concern in space. The other factor is that the transistors on the chips are larger than the ones used on Ea

Less speed = less heat which is surprisingly a large concern in space. The other factor is that the transistors on the chips are larger than the ones used on Earth. I don't remember the specifics but the reasoning was that less transistors would be damaged if a spot on the chip was hit by radiation and built in redundancies would be able to compensate. (Source: had a few EE classes where this kind of thing was brought up been awhile though)