Is reducing horsepower really so important?

“There are three main things that determine engine performance. The first is intake/exhaust efficiency. The second is combustion efficiency, or how well the fuel is burned. And the third is how well horsepower loss can be reduced. The roller rocker arm on these models is a feature that reduces horsepower loss. It is a mechanism that helps create a smoother acceleration feeling by reducing mechanical contact and interference between the moving parts of the engine.”