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Question: iPhone 6S slow and low benchmark scores.

After iOS 10.3 update I some lag experiences and got same benchs scores(very low) with and without lowpower mode!!!

Anyone with the same experience?

Already tried a clean install and the results are the same...

iPhone 6s, iOS 10.3

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Question marked as Solved

My iPhone 6s issue was fixed, the main problem was indeed the battery, but did not replace the battery, the replace the phone.

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Apr 3, 2017 1:23 PM in response to JordanTheOne In response to JordanTheOne

Sorry, I cannot help you, but my iPhone 6 (not 6S) has the exact same problem. I get about half the benchmark score as I did with iOS 10.1. There is no difference when I enable low power mode. Everything seems to run and start slower. I believe the problem is caused by Apple's battery "fix" that came in iOS 10.2.1.

How it works is that it somehow detects that I have a questionable battery, either via serial number or measurements. Then it throttles down the processor speed to avoid power spikes that would otherwise have caused drops in battery voltage. It is these voltage drops that can cause unexpected shutdowns.

So for me, iOS 10.2.1 works better in that there are less shutdowns, but I have to accept that everything now runs at about half the speed, compared to iOS 10.1. This has been confirmed via benchmarks, which now run at about 40-60% of the speed from November last year. The lower the battery, the slower the phone becomes. It can also be seen from how enabling power save mode, no longer changes the benchmark scores. The phone always runs in power saving mode (the processor speed part of power save mode). I am not sure how I feel about this solution.

What can be seen from the public benchmark database for Geekbench, is that there now seems to be two categories of iPhone 6: 1) those that run as before, 2) those that run at about half the speed. I think that those that run at half the speed are being down-throttled to prevent unexpected shutdowns. If anyone can explain these benchmark differences otherwise, please do so. I would have liked my phone to run as it used to when it was new, I can always charge it before it gets to 35% or so, when shutdowns start(ed) to occur. And yes, I have tried a clean iOS install as New Phone, and run all benchmarks with Background App Refresh off and in Airplane mode.

Apr 3, 2017 1:23 PM

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Apr 16, 2017 1:06 PM in response to n808n808 In response to n808n808

Indeed. I experienced the same problems on iPhone 6 on iOS 10.3.1 even 10.3.2 beta 2. It drove me nuts. But I believe you are right. It's logical and the shutdowns don't occur anymore. But it leaves me with a bitter feeling that the phone isn't at it's peak performance anymore.

Massive drops in Antutu and Geekbench. Always changing. Lowest was - 50% perf. drop.

Even on full charge or with power connected the performance won't go to 100%. Maybe 80% max.

And yes, it depends of the battery charge. Lower the battery - lower the scores.

My battery life is estimated to be at somewhere of 83%. Shutdowns we're present on 10.2.

I'm seeing the performance drop using the phone too. First I thought it was the OS. Now, I know.

I understand the idea. It's kind of an elegant solution to resolve the shutdown problem. But it bugs me.

Now my question is ... If I replace the battery, would the CPU continues to throttle like this or will it be normal again ?

Apr 16, 2017 1:06 PM

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Apr 16, 2017 3:34 PM in response to CodrutM In response to CodrutM

I agree, I am really annoyed my iPhone is forced to run in this low power CPU mode. I (almost) always charge the phone before it gets to 30% where the shutdowns sometimes happened, and would have gladly had back its original performance. Sadly, the iPhone 6 is far long out of the limelight, and no one care what Apple does to it to avoid having to replace batteries en masse. If Apple had done this to a newer model, it would have caused quite the furore. As it is, it does not appear to affect all iPhone 6's still in circulation, and for those affected, only a very small minority notices the problem, and if anyone does, they write it off as "normal old cell phone, new OS slowness". I was surprised to see your reply to my post..

You raise a very good question - I have also considered paying for a battery replacement, but since I don't know if it will bring it back to original performance, I put it off for now.

Apr 16, 2017 3:34 PM

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May 14, 2017 12:34 AM in response to n808n808 In response to n808n808

Hi, same issue I had with my iPhone 6 (age 2yrs, iOS 6.2.1). Battery charging cyles 560+ out of 600 - as per Apple Store Support Tool.

Performance was half of the speed before and battery got drained withing few hours with sudden shutdowns.

They have replaced the battery and the performance issue vanished. Speed is back to normal.

Hope this information helps someone.

Bedt Regards,


May 14, 2017 12:34 AM

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May 16, 2017 1:32 AM in response to Marcel-GER In response to Marcel-GER

Hi. Good to know that others like yourself fixed the problem by swapping the battery via apple service. I hoped at the beginning it will work in my situation and not getting stuck with half the CPU speed. It's all good know. Phone working as it should.

May 16, 2017 1:32 AM

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May 23, 2017 1:23 PM in response to Anperis In response to Anperis

The discussion was originally longer, but has been censored by Apple.

However, the short answer is, if you replace the battery, and according to Apple's rules, I can only advice that you go to an Apple store to get this done, your phone will likely get back up to full speed, as the phone will then no longer be throttling the processor speed. That was my experience, and that of a couple of other people in this thread, but I can of course not guarantee your results.

May 23, 2017 1:23 PM

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May 23, 2017 2:28 PM in response to tonyisit In response to tonyisit

For more info, see first page of this thread.

Both iPhone 6 and 6S have shipped with bad batteries, but Apple has only voluntarily replaced the battery for free, for a relatively small number of 6S phones. Officially, Apple issued a software fix for the rest of the phones with iOS 6.2.1, without disclosing how it works or which phones it affects. However, it has been deduced that for those phones the firmware detects have questionable batteries, either via serial number or diagnostics, the firmware runs those phones in low power mode at half the processor speed, without telling owners via the normal low power mode UI indication. It's easy to tell via benchmarks though - see first page and also the linked reddit thread.

Good news is that replacing the battery, causes the phone to lift the restriction on processor speed, and it's back to the speed it was supposed to run when purchased. If your phone is out of warranty or you can't explain this to an Apple Store, you have to cover the replacement cost yourself. I tried Apple Support for my phone woes, and officially, there was nothing wrong with it, diagnostics showed all was in order. The work-around, running the phones at half speed, is meant to be perfectly fine.

May 23, 2017 2:28 PM

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Question: iPhone 6S slow and low benchmark scores.