For several years now we’ve tracked the fact that, over time from 2012 onward, Android JavaScript performance has become wildly divergent from iOS JavaScript performance. And not in a good way.

To give you an idea of how divergent it has become, try:

http://emberperf.eviltrout.com

Complex list

Ember 1.11

This is the benchmark most representative of Discourse performance, and the absolute best known Android score for this benchmark is right at ~400ms on a Samsung Galaxy S6. That doesn’t seem too bad until you compare…

iPhone 5 → 340ms

iPhone 5s → 175ms

iPhone 6 → 140ms

iPad Air 2 → 120ms

iPhone 6s → 60-70ms

In a nutshell, the fastest known Android device available today – and there are millions of Android devices much slower than that out there – performs 5× slower than a new iPhone 6s, and a little worse than a 2012 era iPhone 5 in Ember. How depressing.

We’ve done enough research to know this issue is not really specific to Ember, but also affects Angular and most other heavy/complex JavaScript on Android. Why?

Part of it is indeed Chrome/V8 JavaScript optimization issues on Android as you can see from this AnandTech Galaxy S6 review. Note the browser used:

It’s also partly because single core performance on Android is falling way, way behind iOS. Notice that the flagship Android device barely has the single core grunt of an old iPad Mini based on the old A7 core. Compare single core Android GeekBench versus single core iOS GeekBench:

It seems the Android manufacturers are more interested in slapping n slow CPU cores on a die than they are in producing very fast CPU cores. And this is quite punishing when it comes to JavaScript.

This is becoming more and more of a systemic problem in the Android ecosystem, one that will not go away in the next few years, and it may affect the future of Discourse, since we bet heavily on near-desktop JavaScript performance on mobile devices. That is clearly happening on iOS but it is quite disastrously the opposite on Android.

I am no longer optimistic this will change in the next two years, and there are untold millions of slow Android devices out there, so we need to start considering alternatives for the Discourse project.