The iPad and its Performance

Apple knows how to make things feel fast. It’s all about making animations as smooth as possible and making sure that the UI always responds consistently. Apple isn’t perfect in this regard, but it does pay more attention to detail here than most other companies.

On the iPhone, scrolling is always smooth, swiping between home pages feels quick, apps launching are always well animated. The same is (mostly) true for the iPad, but thanks to a faster processor, many of these animations are physically faster. Bringing up the home screen is lightning quick, as is swiping between them. Scrolling is also very smooth, so much in fact that I found myself scrolling through emails and pages just because the animation was done very well.

There are some rough edges of course. While swiping between home screens is nice and fast, bringing up the quick search screen is choppy (not Android choppy, but choppy for the iPhone OS). The same is true for some other apps, particularly 3rd party ones. The latter point makes sense given that developers haven’t had much time with the device, but Apple not ensuring a perfectly smooth UI across the entire OS is telling.

Apple tends to move engineering resources around the company. The iPhone launch delayed the OS X launch that same year. And the iPad launch surely had some impact on other products. Or is it the other way around? Later this week we’ll see Apple preview version 4 of the iPhone OS, which implies a release sometime in the coming months (June?). An on-track iPhone OS 4 release could explain some rough edges with the shipping iPad, as well as why we don’t seem to have a plethora of amazing apps from Apple at launch.

Despite my nitpicking, this thing is definitely faster than the iPhone 3GS and even the Google Nexus One. Surfing the web, loading applications or generally just interacting with the device. Going to a 3GS from a Nexus One feels slow, going to a 3GS after using the iPad just feels wrong.

But with a larger screen you get the desire to want to do more and expect more from the iPad. I would say that in this sense the performance is a letdown. The A4 is speedy but not quite fast enough for this size of device.

  iPad (Apple A4) Google Nexus One (Qualcomm QSD8250) iPhone 3GS (ARM Cortex A8) iPhone 3G (ARM11)
Manufacturing Process 45nm 65nm 65nm 90nm
Architecture In-Order In-Order In-Order In-Order
Issue Width 2-issue 2-issue 2-issue 1-issue
Pipeline Depth ??-stage ??-stage 13-stage 8-stage
Clock Speed 1GHz 1GHz 600MHz 412MHz
L1 Cache Size ?? ?? 32KB I-Cache + 32KB D-Cache 16KB I-Cache + 16KB D-Cache
L2 Cache Size ?? ?? 256KB N/A
GPU PowerVR SGX Adreno 200 PowerVR SGX PowerVR MBX

To figure out where the iPad falls in the grand scheme of things I ran a number of web page load tests and browser benchmarks. To remove the internet from the equation, I loaded all pages off of a server on my own network. This is as close to a pure CPU and OS/browser benchmark as we’ll get.

Given that the iPad runs off smartphone hardware, the obvious comparisons are the iPhone 3GS and Google’s Nexus One. The former is based on a 600MHz Cortex A8, while the latter uses Qualcomm’s 1GHz Snapdragon QSD8250 running Android. Oh and there’s just one more thing:

This is ASUS' Eee PC 1001P. Priced below $300 it is the epitome of the netbook. Low cost and functional, but without looking overly cheap. Based on Intel’s Atom N450 processor this should put things in perspective. I ran the same set of benchmarks on it that I ran on the rest of the platforms. I used Chrome running on Windows 7.

  Apple iPhone 3GS Google Nexus One Apple iPad ASUS Eee PC 1001P
AnandTech Front Page 4.5s 4.3s 3.1s 1.2s
CNN Front Page 5.4s 4.4s 3.9s 2.8s
CNN Front Page 3 8.7s 6.8s 6.3s 3.5s
Facebook 2.5s 2.4s 2.0s 1.4s
MSN 10.5s 5.1s 5.0s 2.8s
Yahoo! 1.9s 1.6s 1.4s 0.8s
Engadget 15.0s 11.6s 11.1s 4.8s

To make this data easier to read I averaged all of the numbers for each device, normalized them to the iPhone 3GS (in terms of % faster) and put the data in a graph:

And now you see why I said the A4 does well against smartphones, but doesn’t cut it for the screen size of the iPad. While the iPad is 46% faster than the iPhone 3GS and 14% faster than the Nexus One on average, the Eee PC is 87% faster than the iPad. It is noticeable!

Real world JavaScript performance is also no contest between the A4 and Intel's Atom:

If Apple doesn't have plans to use Moorestown (or a derivitive) in its iPad at some point, I would be sorely disappointed in the company's ability to make intelligent hardware decisions.

I will give Apple credit, the iPad feels quick in most cases, which is probably why the sacrifice to go with a lowly Cortex A8 was made. However, when it comes to browsing the web, there’s a tradeoff. It’s much better reading web pages on the iPad, but it’s much faster on the Eee PC.

The comparison gets more complex when you look at things like application launch times. It takes the iPad 3 seconds to launch Pages, and less than 1 to launch Safari. If the application was previously in memory, the Eee PC can fire up Chrome in less than a second, otherwise it takes longer depending on what Windows decides to do with the disk at that moment. And launching Word from scratch takes much longer than 3 seconds.

Apple is relying on solid state storage and a very lightweight OS while netbooks usually have terribly slow hard drives and a bulky software stack. It’s a ginormous tradeoff. Web pages load quicker on a netbook, but are easier to read/navigate on the iPad.

What Apple absolutely needs in here is an Atom CPU. Apple buys itself a lot of leeway by using a very lightweight OS, but when a web page still takes a dozen seconds to load - you feel the pain. While I realize that Atom hasn't been suited for such an application until now, there's no reason Apple should've picked the A4 over Moorestown. Moorestown can fit in devices far smaller than the iPad, and would make this thing perform more like (and better than in some cases thanks to the OS) a netbook. I laughed when Jobs said that netbooks don't do anything well. While I'd agree a lot of the time, here they do seem to load web pages faster than the iPad.

The Silicon - Meet the A4 Honest Apple: Battery Life
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  • Anand Lal Shimpi - Wednesday, April 7, 2010 - link

    I definitely appreciate the corrections :) Fixed!

    Take care,
    Anand
  • odditude - Friday, April 9, 2010 - link

    Bottom of P12: "Most developers just got access to the iPad on " - unfinished fragment
  • afkrotch - Thursday, April 8, 2010 - link

    I found a bunch of errors in the article, but I chalked it up to him trying to use the iPad for actual work. Something it apparently sucks at.
  • strikeback03 - Friday, April 9, 2010 - link

    lol, I thought the article might have been a little rushed, kinda like the iPad. Great insight and content, but could have stood for a little more editing.
  • CyberMonk - Wednesday, April 7, 2010 - link

    According to Apple, you're incorrect about the iPad not having an oleophobic coating. From the iPad's tech specs page: "Fingerprint-resistant oleophobic coating"
  • solipsism - Wednesday, April 7, 2010 - link

    3rd-party accessory are allowed. Bluetooth keyboards already work with it and Apple licenses the iPod Dock Connector port so there is nothing stopping anyone else from selling their own keyboard, dock, or whatever, which I hope they do as the one Apple supplies has no option for folding down for easy travel.

    You can even use a simple USB-A(f)-to-USB-A(f) coupler for syncing your photos instead of paying for Apple's adapters. There are other options that already exist in this arena for USB.
  • Grump642 - Wednesday, April 7, 2010 - link

    Think I will hold on till the HP Slate comes out. It will have most of the things on it that the iPad is missing.
  • afkrotch - Thursday, April 8, 2010 - link

    If the HP Slate runs Win7, I'd be all over it. I picked up a HP TM2, but the touchpad was broken on it. I went for a replacement, but none available. I'm waiting for more to come in stock, hopefully that's before the Slate comes out.

    I tend to jump right into purchases and I'd rather see how the Slate does. If it comes out before the TM2 comes in stock, that might not happen.
  • joe_dude - Wednesday, April 7, 2010 - link

    That was a very detailed review. Only disagree on the gaming aspect. While the touch interface is cool, the CPU, GPU & memory seriously limits its potential. Others have already mention that.

    http://www.gamesradar.com/f/real-gamers-review-the...

    Nothing against retro-gaming, but Worms, C&C, RE4, Scrabble, etc. are netbook quality at best.
  • ekul - Wednesday, April 7, 2010 - link

    Anand,

    An excellent article as usual. While most of the ipad reviews have been quite through you have managed to discuss elements of the device no one else has touched on.

    That said I have to disagree with your plea for a moorestown cpu. Even with moorestown being so much more efficient than regular atom based systems it can't touch a cortex a8 for idle or load power draw. Combine that with smaller packaging for arm, lower costs and true SoC designs and it isn't even a contest. The price is lower performance but I'll take the trade for battery life.

    Keeping ipad the same architecture as existing iphone OS devices is a big bonus as well, lowering development costs for both apple and app developers. ARM is also providing an excellent upgrade path from a8 to the a9 SoCs that are sampling now and should be in devices shortly.

    Once there is a true SoC design based on atom it might be worth considering but for now it's just not ready

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