From In The Plex pg 185:
Sergey Brin even put a label on his cofounder’s frustration at the tendency of developers to load more and more features into programs, making them run way too slowly. Page’s Law , according to Brin, was the observation that every eighteen months, software becomes twice as slow. Google was determined to avoid this problem. “We want to actually break Page’s law and make our software increasingly fast over time,” says Brin.