/ Technology

The operating system update lottery

Have you ever hit ‘update’ on your smartphone or tablet only to find that your device seems to end up worse rather than better? We shared this suspicion, so we put these updates to the test.

My phone is pestering me to accept the latest upgrade. I know I should because it’ll give me all the latest security patches and help protect my phone from leaky apps siphoning off my personal data.

But it’ll probably give me a few features I’m not interested in as well. For instance, I’ve got a yellow iPhone 5c and I love it, but updating it will add the Apple Watch app. And since I have no intention of buying the pricey Apple Watch, this app will take up valuable memory despite remaining unclicked.

That’s not the only thing putting me off from tapping the update button – sometimes upgrading can negatively impact key elements of your phone, such as its speed and battery life.

Does upgrading really downgrade your device?

To find out whether there was any truth to these suspicions we put the theory to the test in our lab.

We retested the battery life, processor speed and storage space on 26 smartphones and tablets after updating them to the latest version of Android or iOS. Of the 26 that we tested, 24 gained a lower mark in at least one of those categories, and 17 scored worse in two or more categories. In some cases they lost just a few minutes of battery life, or a few hundred megabytes of storage. But we also found some bigger differences – you can read all about these on our sister site Which? Tech Daily.

Pick and mix updates

So we’d like to see users given some control over what updates they apply to their smartphones. While security fixes should be mandatory, other updates such as new apps or cosmetic changes should be optional. And all updates should maintain or improve performance, rather than causing it to deteriorate. If manufacturers can’t guarantee this, then we think users should be able to roll back their device to the previous operating system.

Do you dutifully update your phone’s or tablet’s operating system? Did it make your device better or worse?


I had already read the article on Which? Tech Daily and seen the impact that updates can cause on battery life and available memory for apps, images, etc. Thanks very much to Jessica for starting what I believe is an important discussion. I update the operating system on my iPhone and iPad fairly promptly but not immediately, just in case there is a major problem with the new release. I don’t put heavy demands on either and so far have had no problems.

I believe that it is vital that the user has the opportunity to reinstall an earlier operating system – particularly with computers. My main concern is that updating a computer OS may prevent (paid for) software working. Online information can be useful but the only way to find out for sure is to do the update and cross your fingers.


Jessica: perhaps you can clear up some confusion for me. When you say we put the theory to the test in our lab can you confirm if this is Which?’s very own lab, or is it an outside agency? I wasn’t aware Which? still retained any of its own testing facilities.

You say you examined the impact of upgrades on three parameters: battery life, processor speed and storage space, and that almost all stored a lower mark on at least one category. But, in fact, the processor speed wouldn’t have changed in any way at all: that’s a pre-set function in the factory, so you would only be able to test two parameters.

Every upgrade does add something, of course, but more often than not it’s simply the tech companies attempting to stay ahead of the game with regard to the criminal fraternity. For reasons that would take too long to explain there is no such thing as a ‘bug-free’ or ‘totally secure’ operating system. It’s in the very nature of the game that there will always be ways that systems that can be compromised. These are often only discovered after a product has been released, which is one reason why you have repeating upgrades. Every security upgrade is going to change the ways in which your system operates: that’s inevitable, and almost all of the time it’s going to take up a little more space and make the battery work just a little harder.

If you’re making the point that you ought to be able to select which bit gets upgraded – such as the Apple Watch capability, for instance – then perhaps you should, but sometimes security upgrades are contingent on a new aspect being added. It’s by no means a simple problem.




Hi Ian,

Indeed this is a complex problem. We agree that security fixes are essential in keeping your device safe and should be pushed out to all phones and tablets. Our grievance is with the extra features and new apps, such as the Apple Watch app, which take up space yet and may remain unused.

We feel that you should get the choice to decide whether you want these extras or not. And when it comes to essentials such as battery life, the manufacturers should make every possible effort to ensure that this does not deteriorate.

With regards to the processor speed, I raised your question with Jess who explained that we re-ran the industry standard speed tests to see what impact the update had. The operating system governs how the processor is used and will therefore have an impact on how fast the device manages standard tasks.

And when it comes to testing, we use independent labs which means that we can ensure that the most qualified and experienced people in their fields test each product. Further information on our testing can be found here: http://www.which.co.uk/about-which/who-we-are/which-research/lab-testing/


Lauren- your first paragraph is apt as regards apps in the Apple operating service . New data from a business security communications company put out for the business community in regards to apps on all systems puts Apple OS as the worse system for vulnerabilities at= 384 (mac Os X + its smaller derivative ) Flash Player dropped to third = 314 . I have the full list if anybody is interested.


There are several issues with that list of Common Vulnerabilities and Exposures (CVEs). The first is that the survey makes no distinction between severity of vulnerabilities in the list. A low-risk vulnerability (for example, something that can only be exploited by an authenticated local user with administrative privilege) is not the same as a remote code execution bug that’s easily exploited.

Second – and this applies to all platforms – many security bugs are cross-platform. A good example is libpng, which is everywhere from browsers to smart-watches. It may have had only had four advisories in 2015, but that will have drawn patches from a lot of other vendors.

Third: CVE Details seems arbitrary in its assignment of CVE to project. Hence, for example, a bunch of LibreOffice/OpenOffice bugs are counted as Debian CVEs, as are some Oracle MySQL bugs.

Fourth: CVEs only count reported vulnerabilities. They don’t count anything that’s being hoarded, whether by security agencies or by black-hats, for example. And there’s nothing good to come out of turning CVEs into some kind of marketing scorecard.

As everyone’s favourite infosec account put it:

As this chart (rather than the list favoured by most outlets) shows, Microsoft and Adobe both out-CVEd Apple for vulnerabilities “by vendor” across CVE Details’ Top 50.

Even that’s a problematic count. For example, by restricting the summary to CVEs in the Top 50 list, the summary is very kind to Cisco. Its IOS only racked up 84 vulnerabilities, but across all products, The Borg had a very busy 2015, recording 488 CVEs.

In short, as the Register put it “This Meaningless league table sparks silly schadenfreude”

With thanks to the Register.


Thank you for your explanation, Lauren, but when you say “With regards to the processor speed, I raised your question with Jess who explained that we re-ran the industry standard speed tests to see what impact the update had my concern was with the wording used in the article, which was clearly incorrect. I appreciate that the Independent Laboratory which ran the tests did not check processor speed. Had they done so, they would have noted it remained constant. What they checked was something very different: it was how the update affected the overall speed of the device to perform what the laboratory describes as “industry standard” tasks.

This may not seem important to many, but I believe words and their meanings are extremely important. There ought to have been no mention whatsoever about “processor speed”, since it’s almost impossible to check without dismantling the device and extracting the CPU. What they (and you) checked was how quickly the device performed on the same tasks prior to and immediately after an update. And it would have been much simpler (and far more honest) to say that.

And herein lies another problem. Since neither you nor they can be sure exactly what the update changed you cannot be sure any change was due to the installation of extra bits – such as the Apple Watch. You might think ‘common sense’ says it must be the update, yet ‘common sense’ suggests the sun moves round the Earth.

On the new features aspect, that, again, is no simple thing. And there are good reasons why it isn’t. Making software and computers is a highly competitive business, although only Apple does both. However, all software companies have to design their products to stay ahead of the game and, on the internet side of things in particular, changes are needed to deal with the varying design standards used by the browsers. That alone can slow your device down, but as processor speeds continue to increase browsers and software authors continue to design more features into their work. It’s a never-ending game of catchup. Consumers should not be led into believing that anything else is possible.

I do agree that cosmetic updates should be optional, but here’s another question: what, exactly, qualifies as ‘cosmetic’? Software’s appearance through its GUI is now largely indistinguishable from its function. How then is the consumer able to differentiate?

But the language and terminology must be more accurate. Which? used to enjoy an enviable reputation for accuracy and impartiality but dubious reviewing of this nature can only do a lot of harm to a hard earned standing.


I dont know why I got Ian,s above post emailed to me as it is 6 days old nevertheless I am always up for a challenge . As regards the processor speeds being difficult to access or should I say the basic C PU speed ,yes Apple make it very difficult to find out the type of processor fitted . But Apple /Windows/Android all use the ARM processor , the latest info (and that is about 2 years old ) is that they are dual core -some 4 core with a basic speed of 1.8 G ,for those wanting info about their processor a Japanese tech engineer has provided a download of -CPU identifier especially for mobile phones ,you install the app and it checks out your CPU . Knowing the basic speed and cores etc does help in generating a scale of performance of a mobile phone . Its a pity they are not like Intel and AMD in computers I have a full list of speeds of all their CPU,s and that is used to judge performance in every PC tech site I visit . Having said that yes , Windows for example due to “updates ” can slow the fastest gaming PC down to a crawl if they are faulty or if MS dont like y