Software that’s speedy usually means it’s focused. Like a good tool, it often means that it’s simple, but that’s not necessarily true. Speed in software is probably the most valuable, least valued asset. To me, speedy software is the difference between an application smoothly integrating into your life, and one called upon with great reluctance. Fastness in software is like great margins in a book — makes you smile without necessarily knowing why.
The impact of speed in software is on the user perception of the quality of the software.
Nice read: https://craigmod.com/essays/fast_software/