“Before the PLT, our editorial process was primarily concerned with feature implementation, bug fixes, and web standards compliance—how well the browser did what it was supposed to do. These were all qualitative measures. The PLT checked for speed, a quantitative test, and it introduced an independent evaluation to every code change we made. Correctness and speed now went hand in hand. Don held that if we heeded the PLT without fail and rejected any code changes that made our code slower, only two things could happen. Either the browser would stay the same speed . . . or it would get faster. He would tap his index finger to his temple to punctuate his explanation of this sneaky logic. From the day the PLT was finished, Don declared, our browser would become faster by never getting slower. It was his Zen koan.”