React vs. Object.observe()
Object.observe() and React are actually aimed at solving different problems. If we're going to mention React, I would say..
"In a test, dirty checking took 40 milliseconds compared to Object.observe’s 1 to 2 minutes. In other words, Angular became 20 to 40 times faster while using Object.observe." should read "Object.observe's() 1 to 2 milliseconds"