Before I dive into the numbers, let’s talk briefly about what makes the iPhone 3G (and 2G) fundamentally different from the 3GS. The iPhone 3G, like the 2G, is based around a 412 MHz ARM11 family Samsung SoC which implements the ARMv6 instruction set. It’s got 128 MB of LPDDR1. By contrast, the iPhone 3GS uses a 600 MHz ARM Cortex-A8 family SoC which runs the ARMv7 instruction set, and packs 256 MB of LPDDR1. The iPhone 4 similarly runs ARMv7 code.

By nature of the two platforms running different instruction sets, their underlying iOS kernels are completely different, even though ARMv6 is a subset of ARMv7. In all likelihood, Apple embraces ARMv7 for speed gains on 3GS and 4, and therefore has to keep a separate kernel for ARMv6. That applied with iOS 3.x and applies the same way with iOS 4.x.

For whatever reason, it seems as though the kernel for ARMv6 devices like the iPhone 3G weren’t quite as optimized as they could have been. As a result, performance on iOS 4 with the iPhone 3G was sluggish.

Speed Testing the Platforms

Even while waiting in line for the iPhone 4, numerous iPhone 3G users I talked with noted a dramatic slowdown. Using one, I was amazed how sluggish things like even jumping in and out of the messaging application were. At the time, I wasn’t sure how much of this to attribute to the iPhone 3G just being an older device, or the iOS 4.0 update. 

iPhone 3G users aren’t asking much, they just want the original speed and responsiveness of their devices back. For these tests, I borrowed a friend’s iPhone 3G and ran through a gamut of tests on iOS 3.1.3, iOS 4.0.2, and the iOS 4.1 GM which should be released September 8th. I also ran tests on an iPhone 3GS running 4.1 GM, though I’ve excluded results in two tables because the numbers destroy the dynamic range on the graphs for seeing change on the iPhone 3G.

iPhone 3G, iPhone 3GS, iPhone 4

Note that downgrading the iPhone 3G is easy since Apple isn’t enforcing SHSH blobs on it. If you can grab the image from any number of thoughtful repositories online, you can restore and downgrade with it. You might get stuck inside recovery mode at the end - but for that, simply use RecBoot.

Browser Testing

For all of these tests, I used a completely fresh, brand new restoration image with no other installed applications and connected to my 802.11n wireless network. I run tests three times and average, throwing out any outliers. Note that launching from a fresh install is critical on iOS as the platform saves a screenshot when closing, and immediately open that when relaunching so successive launches feel faster. 

Our first test is the SunSpider JavaScript benchmark:

Unsurprisingly, the iPhone 3G on 4.0.2 and 4.1 beats 3.1.2. I say unsurprising because iOS 4.x brings a new version of WebKit with faster JavaScript engine. This is actually the one place where the 4.0.2 update helped the iPhone 3G. Note that the iPhone 3GS runs this test nearly 3x faster, taking 14707.8 ms. 

Next up is Browsermark, which spits out an overall score representative of overall browsing responsiveness. There’s some JavaScript, some parsing, some rendering - it aims to be an all around general speed benchmark. 

This is more along the lines of what people have been reporting with the iPhone 3G, though it isn’t quite as pronounced. iOS 3.1.2 scores higher than 4.0.2, but 4.1 closes the gap some. It still isn’t quite there, but has improved. 

A similar test is to see how fast Safari rotates from landscape to portrait. On iOS 4.0.2, it’s measurably slower than 3.1.3, but how does 4.1 fare? Here we start the clock right as we rotate, and stop as soon as the page has rendered completely - you can tell when the text goes from fuzzy to sharp when Safari has completely rendered the page in the new orientation. 


Here iOS 4.1 gets us close to how snappy 3.1.2 was but remains just a tad slower.

Faster Application Launches
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  • Brian Klug - Tuesday, September 7, 2010 - link

    Much thanks for letting me borrow your iPhone 3G ;)

  • xenol - Tuesday, September 7, 2010 - link

    I noticed the slide mentioned the camera can take HDR photos. How?
  • chdude3 - Tuesday, September 7, 2010 - link

    I believe that's for iPhone 4 only.
  • Stuka87 - Wednesday, September 8, 2010 - link

    It takes three photos. Normal, over exposed, and under exposed, then uses an algorithm to put them together.

    But I don't recall it being iPhone 4 only, but I dont have 4.1 installed yet.
  • Brian Klug - Thursday, September 9, 2010 - link

    The other commenters so far are correct - HDR is an iPhone 4 only feature.

    At least from iOS's perspective, that is ;). I've already heard direct discussions of a simple Cydia program being in the works on 4.1 jailbroken (when that happens) to make it work for the 3G and 3GS.

  • crimson117 - Tuesday, September 7, 2010 - link

    I have a 3G running iOS 4.0.2, and yes it's slowwwwwwer than it used to be.

    The things I'm sure are new additions with iOS 4 are:
    - 1st letter lag when entering a search term in safari. Actually, it's more like second-letter lag: the first letter is displayed quickly, but all subsequent letters I type take several seconds to show up. I get the feeling that this is due to a very slow initialization of the auto-suggest feature, perhaps related to re-establishing an internet connection after my phone has been idle for a while.
    - Random 5-15 second freezes when scrolling. Often happen in Safari, or in iReddit or Alien Blue (which use embedded safari windows).

    And the worst part about these things is that the OS doesn't seem aware (and also doesn't seem to care) that it's making the user wait for 5-15 seconds without any warning or explanation.

    If there's a step involved in the safari search box such as "Initialize search suggestion dictionary" then if that's about to happen, the OS should dim the screen and put up a message saying that's what it's doing. Then the user would know which part is slow, and perhaps could push apple or the app's developer to fix it. Perhaps the OS isn't even aware that it's hanging for 5-15 seconds?
  • chdude3 - Tuesday, September 7, 2010 - link

    Or being in the middle of typing an email when things will freeze up again for several seconds (this was usually in the order of 5 seconds) before the phone would become responsive again. It wasn't just Safari - any application exhibited this behaviour. The timing for the freezing did not appear to have a pattern at all, but it made the phone useless. I got so tired of sitting there waiting for it to let me use it again that I went for the downgrade.

    Sometimes it'd freeze without being in the middle of an operation - I'd be reading text within an application and hit a soft button to, say, return to a previous page and the phone would simply sit there for several seconds before responding.

    I can't believe that it got through any type of QA with those types of defects.
  • Stuka87 - Wednesday, September 8, 2010 - link

    I actually get this on my 3GS with 4.x (I have not yet put on 4.1). Sometimes mail will lock up for 20-30 seconds before I can finally do something. I have not noticed it in other apps, but mail for sure on many occasions. So the mail issue may be a mail issue, or could be the 3GS can have the same pausing issues as the 3G.
  • icrf - Tuesday, September 7, 2010 - link

    I have an iPhone 3G and never upgraded to iOS 4, and after reading this, I won't update to iOS 4.1 either. It's already a sluggish device to me, but it's a corporate device for which I barely have an official use, so I've no cause for demanding an update.
  • Henk Poley - Tuesday, September 7, 2010 - link

    I wonder if Apple will break out of character and release iOS 5 earlier than with the next iPhone, to get around this line in their Software License Agreement:

    "Apple will provide you any iPhone OS software updates that it may release from time to time, up to and including the next major iPhone OS software release following the version of iPhone OS software that originally shipped from Apple on your iPhone, for free."

    iPhone 3G 8GB were still sold here slightly more than a month ago.

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