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Android UI will never be completely smooth because of the design constraints I discussed at the beginning:
- UI rendering occurs on the main thread of an app
- UI rendering has normal priority
Even with a Galaxy Nexus, or the quad-core EeePad Transformer Prime, there is no way to guarantee a smooth frame rate if these two design constraints remain true. It’s telling that it takes the power of a Galaxy Nexus to approach the smoothness of a three year old iPhone. So why did the Android team design the rendering framework like this?
Work on Android started before the release of the iPhone, and at the time Android was designed to be a competitor to the Blackberry. The original Android prototype wasn’t a touch screen device. Android’s rendering trade-offs make sense for a keyboard and trackball device. When the iPhone came out, the Android team rushed to release a competitor product, but unfortunately it was too late to rewrite the UI framework.
This is the same reason why Windows Mobile 6.5, Blackberry OS, and Symbian have terrible touch screen performance. Like Android, they were not designed to prioritise UI rendering. Since the iPhone’s release, RIM, Microsoft, and Nokia have abandoned their mobile OS’s and started from scratch. Android is the only mobile OS left that existed pre-iPhone.
So, why doesn’t the Android team rewrite the rendering framework? I’ll let Romain Guy explain:
“...a lot of the work we have to do today is because of certain choices made years ago... ...having the UI thread handle animations is the biggest problem. We are working on other solutions to try to improve this (schedule drawing on vsync instead of block on vsync after drawing, possible use a separate rendering thread, etc.) An easy solution would of course to create a new UI toolkit but there are many downsides to this also.”
Romain doesn’t elaborate on what the downsides are, but it’s not difficult to speculate:
- All Apps would have to be re-written to support the new framework
- Android would need a legacy support mode for old apps
- Work on other Android features would be stalled while the new framework is developed
However, I believe the rewrite must happen, despite the downsides. As an aspiring product manager, I find Android’s lagginess absolutely unacceptable. It should be priority #1 for the Android team.
When the topic of Android comes up with both technical and nontechnical friends, I hear over and over that Android is laggy and slow. The reality is that Android can open apps and render web pages as fast or faster than iOS, but perception is everything. Fixing the UI lag will go a long way to repairing Android’s image.
Beyond the perception issue, lag is a violation of one of Google’s core philosophies. Google believes that things should be fast. That’s a driving philosophy behind Google Search, Gmail, and Chrome. It’s why Google created SPDY to improve on HTTP. It’s why Google builds tools to help websites optimize their site. It’s why Google runs it’s own CDN. It’s why Google Maps is rendered in WebGL. It’s why buffering on Youtube is something most of us remember, but rarely see anymore.
But perhaps the most salient reason why UI lag in Android is unacceptable comes from the field of Human-Computer Interaction (HCI). Modern touch screens imply an affordance language of 1 to 1 mapping between your finger and animations on the screen. This is why the iOS over-scroll (elastic band) effect is so cool, fun, and intuitive. And this is why the touch screens on Virgin America Flights are so frustrating: they are incredibly laggy, unresponsive, and imprecise.
A laggy UI breaks the core affordance language of a touch screen. The device no longer feels natural. It loses the magic. The user is pulled out of their interaction and must implicitly acknowledge they are using an imperfect computer simulation. I often get “lost” in an iPad, but I cringe when a Xoom stutters between home screens. The 200 million users of Android deserve better.
And I know they will have it eventually. The Android team is one of the most dedicated and talented development teams in the world. With stars like +Dianne Hackborn and +Romain Guy around, the Android rendering framework is in good hands.
I hope this post has reduced confusion surrounding Android lag. With some luck, Android 5.0 will bring the buttery-smooth Android we’ve all dreamed about since we first held an HTC G1. In the mean time, I’ll be in Redmond working my butt off trying to get a beautiful and smooth mobile OS some of the recognition it deserves.
