The article is right about Javascript, but wrong about why mobile web apps are slow. Most mobile web apps are not games nor image processing apps, they are simple content sites or form-driven applications that are not CPU bound and don't use a lot of JS. These apps are subjectively slower because of browser layout engine performance.<p>Even on "heavy" JS apps, I've heard it said they only use 30% CPU. So if 70% time is not spent in JS, even if you run that 30% 50 times faster, at best you get a 42% speedup from 50 times better CPU performance.<p>I feel the author has caused many to have the wrong take-away message, and the anti-web contingent are lapping it up. Mobile Wep Apps can be made to perform fast today, but it takes way way too much effort to tweak the CSS/DOM manipulations to avoid jank. Consider for example the need to manually "hint" you want GPU compositing by using identity CSS3 transforms.<p>The rendering engines need to get better with leveraging the GPU and avoiding work when they don't need to.<p>If you want to see what a herculean effort can achieve, see Sencha's FastBook.<p>Basically, the author is right, but I think it's a red herring given that when people talk about "slow mobile web apps", 99% of the time, they are not talking about an Instagram written in JS, or AngryBirds in Javascript, but some basic news feed app.