OK, let's put this debate to bed. Here's proof black is the fastest color.

Light travels at a constant speed in vaccum... 3 x 10^8 m/s...
But in media like air, glass, different wavelengths in the electromagnetic spectrum travel at different speeds.
Refractive Index n is inversely proportional to wavelength of light.
But refractive index = Speed of light in Vaccum/Speed of light in medium
Hence, speed of light in media is directly proportional to wavelength...
Since wavelength increases from Violet to Red,
Red travels the fastest...
Violet travels the slowest...
Black is the absence of color (and is therefore not a color)
Explanation: When there is no light, everything is black, therefore black travels faster than light.