I have another idea. The prediction could be configurable, perhaps some mobile phones with more CPU and memory don't need to do prediction.

https://github.com/mozilla-b2g/gaia/blob/master/build/applications-data.js#L126

prediction : {
   enabled: true, // by default
   panning_lookahead: 15
}

```js
var predictedDeltaX = (function predictedDeltaXWrapper() {
    if (!isTouch || !prediction.enabled) {
      return function(evt) { 
         return getX(evt) - startEvent.pageX;
      }
    } else {
       return function(evt) { 
           // Do prediction
       }
    }
})();
```