Since the advent of video games like Doom, it is First-Person Shooter.

Where did you see this and in what context?

From whatis.techtarget.com:

foot-pound-second system of units

The foot-pound-second (fps) system of units is a scheme for measuring dimensional and material quantities. The fundamental units are the foot for length, the pound for weight, and the second for time.

The fps system has two variants, known as the American version and the Imperial version. Neither scheme is often used by scientists nowadays; the International System of Units (SI) is preferred. However, fps units are used to some extent by the general public, especially in the United States.

I would bet (but cannot verify) FPS is a type of Fire-Proof-Silica Brick.

Try searching for "Refractory Bricks"

FPS - Definition by AcronymFinder