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I have a webapp for iPod touch and iPad. Works like a charm on iPad 1 and iPad 2. Now I have tested on a new iPad (iPad 3, iPad HD whatever name to be used) and I see that the painting of the screen is slow. I can see kind of blocks being painted one by one.

Anyone knows how I can get the painting of the screen faster than iPad 1 and 2 instead of slower ?

EDIT: Bounty expiry The bounty has at least given some answers, although they are not sufficient to award the bounty. The question remains open.

bart s
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  • Same here, have you found a solution for the performance problem? – Vilius May 21 '12 at 06:19
  • nope, still no solution here. – bart s May 21 '12 at 06:22
  • I have the same problem in iPad3(ios5),I replace all the rich html with just a simple ul/li list,but it still works slowly,have you solved it ? – Lanston Aug 19 '13 at 05:05
  • @Lanston: Upgrade to iOS6 will solve this. the JavaScript engine in iOS6 is much faster than in iOS5. I did not find a solution for iOS5 (and now wondering what will happen with the upcoming iPad Mini with retina) – bart s Aug 19 '13 at 07:10
  • @barts,did you tried using iScroll to boost up the performance – Lanston Aug 19 '13 at 09:19
  • @Lanston the slow painting was not specific to a scroller, but to the entire page. I added an answer to [one of your questions](http://stackoverflow.com/a/18328984/474535) about forcing hardware acceleration on an iScroll. That can apply to an entire document as well. – bart s Aug 20 '13 at 09:11

3 Answers3

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We had similar problem in our application, and tried some optimizations, here are the two most effective approaches:

  1. Avoid using CSS3 effects. We used a lot of CSS3 shadows in previous versions, which slowed down rendering process on iPad 3 a lot. After replacing those shadow effects with background images, performance got greatly improved on iPad 3.

  2. Optimize Javascript. Our application has some scrollable components, whenever user scrolls the component some Javascript code will be executed to do some loading work, like loading images in a lazy way. On iPad 3 scrolling will delay for 500ms when user tries to scroll from one page to the next. Then we found some unnecessary image loading work were performed in the scrolling callback, after removing them, the scrolling performance is acceptable.

These two approaches may be quite specific to our application. Hope they can help you as well.

ZelluX
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  • I have tested this and even though removing shadows (not even using images) is slightly improving the speed, but not sufficient. Still iPad 1 with iOS 5.latest is faster building the screen with shadows than the new iPad without shadows. Your second point is something specific to your application. I appreciate the answer and upvoted. – bart s May 24 '12 at 06:33
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have you checked viewport in your meta?

I am using 

<meta name=”viewport” content=”width=device-width, initial-scale=1, maximum-scale=1″>

I didn't feel any performance overhead. Perhaps some parts of your webapp hit on the weakness of web view.

You may start commenting your HTML until you find your webapp go smooth.

Mickey
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  • I don't see how this meta would make a difference in screen rendering on the new iPad, but for what's worth, yes it is set. Commenting HTML until the app goes smooth means that I have to kill the app's layout and options which of course is not even an option – bart s May 29 '12 at 07:54
  • Have you tried using Instrument to measure CPU usage? I usually use it to measure native app but not tried on web app. – Mickey May 29 '12 at 15:04
  • I compared iPad 1, iPad 2 and new iPad next to eachother. Just a visual check says enough – bart s May 29 '12 at 16:25
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I have updated a New iPad (iPad 3) with iOS 6 and I do not see the rendering problem any-more. I have seen in several articles that the speed of Safari has significantly increased. This performance gain in iOS 6 is solving the problem for my web-app.

As the iPad's we use are dedicated for the web-app, I will recommend iPad 3 only with iOS6.

Thanks for the posts and answers !

bart s
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