Daniel Eran Dilger
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How to speed up your iPhone 3G running iOS4

Daniel Eran Dilger

Many users with an iPhone 3G have found their phone almost unusably slow after upgrading to the latest iOS 4. If you’re suffering with a slow phone, here’s something that’s worked for a lot of people: a cold hard reboot. And turn off Spotlight search.
Simply doing a normal shutdown and restart of the iPhone doesn’t seem to have any real effect, as the iPhone shuts down to a disk image. In other words, a normal restart (pressing and holding the top sleep/wake button until you get the red slider, then sliding it to turn the phone off, and then turning it back on again) just puts you right back to where you were.

In order to force the iOS to rebuild (a step that seems to optimize a variety of things), you have to press and hold the Sleep/Wake button along with the Home button for about ten seconds, which will kill the phone and initiate a reboot.

When it turns back on, it will take a while to boot. My iPhone 4 boots from a cold death in about 30 seconds, but when I did the same to an iPhone 3G, it spent more than four minutes on the Apple logo startup screen before I was returned to the Home screen.

One this happens however, you should notice that things are better optimized and far more usable. Of course, the iPhone 3G hardware is a lot more limited in terms of processing power and available memory, but doing a cold boot after upgrading to iOS 4 at least seems to make it a lot more functionally usable.

Turn off Spotlight Search for a bigger, long term boost

Another tip submitted by readers: turn off Spotlight search indexing. From Settings/ General/ Home Button/ Spotlight search, turn search indexing off for as many items as possible. This reduces the overall workload of the system, so it appears to give an overall performance boost that is significant.

Let me know what you experience in the comments below.

  • Tayster

    First Power On Self Test.

    [That was pretty clever – Dan]

  • Orenge

    Great tip. Two things:

    1. This “forced rebuild” helps with crashes and unexpected reboots too. My iPhone 3G running iOS 4 was never slow in the first place, but it was crashy. This fixed it—and no settings were lost or changed. A harmless procedure.

    2. FWIW, someone on Apple’s boards said to keep holding both buttons down even after the reboot begins, causing the phone to shut off totally (and then you just turn it back on by holding the sleep button). Someone else said to try more than one “forced rebuild” if the first fails. I only needed one myself, but I thought I’d throw these suggestions out there.

  • lefauxfrog

    That seemed to help a little bit so far. I hope it improves scrolling speed in all apps. Thanks.

  • gus2000

    My 3G was very slow, and is now much improved.

    The reset took 2.5 minutes. For laughs I did it again, which took about 2 minutes. I’m not bored enough to do it a third time :P

  • weeraanmelden

    Am I the only one that doesn’t get the “Sim Locked” screen after forcing a hard boot?
    Thanks for the tip. My iPhone 3G was unbearably slow , so hopefully this works.

  • cjlacz

    Trying it now. Mine has been awfully slow with a lot of crashes since the update. I hope this improves things. I’ll report back later.

  • marlowe

    This could only make things worse. You are forcing your iPhone to shut down uncleanly and this could just cause more trouble. If you want to really make a difference Restore the iPhone 3G in iTunes ONLY AFTER YOU HAVE SYNCED ALL IMPORTANT DATA TO YOUR COMPUTER. Then after the restore set your iPhone up as a NEW PHONE. DO NOT RESTORE FROM BACK UP. Then re sync all of your info back to the phone. Doing this will delete your texts and possibly 3rd party app data but it’s much cleaner than doing a “hard reset”. I understand this is a much more destructive way to fix this as far as your settings are concerned but will definitely help more than the “hard reset” which is just a temporary fix at best.

    [Well remember than the iOS was designed to handle a hard shutdown. It’s not exactly Windows 95. – Dan]

  • http://Www.bitburn.org bitburn

    Cool, I’ll try that now. But once this is done, doesn’t the device memory get filled up again, making the phone slow again after a while?!
    Just wondering. Thanks.

    [I haven’t looked closely at what’s going on, but I’m assuming that the boot process cleans stuff up in a way that optimizes the OS for the hardware. This apparently does not happen when you do an upgrade to any existing system. Report back if the problem doesn’t last for long. The next update might also tighten up things a bit – Dan ]

  • gus2000

    That’s weird, my phone came up and said “please run ‘chkdsk c:’ and reboot”. I have a boot floppy, does anyone have a USB floppy drive?

  • imfullofit@gmail.com

    Thanks for the tip!

    I was planning on doing what Marlow is suggesting. I will give this a try first.

    : )

  • duckie

    I tried this cold reboot (twice in a row as recommended by somebody somewhere) last week. It did improve my 3G’s speed for a while but after a couple of days it was back to occasional freezes in Safari and apps sometimes crashing at startup. I have now gone for the restore to factory defaults and rebuild/sync from scratch option, good so far. Fingers crossed.

    Incidentally I thought I’d try the same basic restore with my iPod Touch 1st gen which is still on iPhone OS 2.1 – the responsiveness is now phenomenal. It jumps from screen to screen quicker than my iPhone 3G running v3.

  • edinburghmac

    The benefit of a poor broadband connection!

    When I updated my iPhone3G I ended up having to effectively do this reboot as my broadband service has been so poor for the last year or so that virtually every update I try and download ends up with file corruption. This is what happened with the iOS4 update which effectively bricked my iPhone3G.

    Afte removal of the corrupted iPhone update file and re-download at work I was able to rescue the iPhone3G but had to restore it from backup – the resulting 3G with iOS4 was much snappier than before with 3.1.3. However I’ve subsequently upgraded to iPhone4 and sold the old 3G. For any UK customers wishing to do this I’d recommend checking out Carphone Warehoue’s trade-in deal. You just need to enter your IMEI number and they’ll give you a quote – got £184 from my 3G (over £40 more than O2 were offering).

    As for the broadband issue, an engineer is visiting this weekend to try and get to the source of the problem (can’t believe how much I pay Virgin Media each month for such a crappy service).

  • ShabbaRanks

    My time to shine…

    OK. After all the issues I’ve had with iOS4.0 on my 3G I’ve come up with the following top tips:

    1: If you’re getting a lot of crashes (i.e. “Black Screen Of Death) or freezing, it’s best to reinstall the OS from iTunes. If the problem seems no better following the reinstall, do it again. It can take a number of reinstalls for it to “take.”
    2: If the phone is crashing/freezing about once a day the hard reset is your best option. This should restore performance at the expense of an unusually long reboot time.

    However, in my experience, iOS4.0 will start to freeze/crash/run dog slow again in a couple of days. Hopefully my experience is unique but, if not, your only option is to keep hard resetting the device if the lagging and freezing gets too annoying. Not a great solution and an especially poor work-around for an Apple product but there you go. You could buy an iPhone 4.0 like I’m, sadly, going to do but I’ll understand if the expense makes you baulk at the idea.
    Just be thankful they didn’t put wallpapers on or it might take ten minutes to open the calculator.

  • broadbean

    Hard resets certainly helped my 3G. Been comparing it with the wife’s 3.1.x 3G with apps like the built-in camera and photo album. Now mine even matches or beats hers.

    It will be interesting to see how long this lasts however. Don’t mind hard resetting it every week, but a few times a day would be annoying.

  • gus2000

    Hopefully this is a software bug that will get fixed!! If I wanted to reboot every damn day, I’d buy Windows.

    I’m guessing it’s a memory leak.

  • airmanchairman

    I was pretty patient with iOS4 installation on my 3G, mainly because I was blogging while my 3GS was upgrading and became quickly aware of the problems users were getting on the 3G and some good suggestions to prevent them.

    It’s slightly slower in places, but strangely better in other surprising areas (like X-Plane Flight Simulator runs smoother and better!). Folders is the big win, and I can now control bluetooth headset volume from the handset itself in addition to the headset.

    Oh, and before anyone asks, my 3G will be taking up duties as data store for my musical apps – Line 6 amp settings, MIDI files for composed multi-track songs, guitar effects and synthesizer / sequencer patches, and as earlier generation an Ipod Touch…

  • hrissan

    Immediately after reboot the phone responds much faster.

    I have checked the list of processes with their memory footprints and there is no visible difference before and after reboot. The daemons for unused features, like bluetooth, eat up real memory.

    This makes me wonder what happens when you make a “cold” reboot…

  • SkyTree


    I installed iOS on my iPhone 3GS shortly after backing up purchased Apps. It didn’t require a re-boot and seemed to be working OK. Then it just totally died. I re-booted by pressing the big button and the sleep button.

    Now everything seems to be working as usual, but sometimes slightly faster.

  • http://@jenATL jenATL

    This made a WORLD of difference on my 3G. Hope it lasts.

    Many many thanks for sharing this!

  • http://www.lowededwookie.com lowededwookie

    Sorry Marlowe but you’re wrong. This is something Apple includes as part of its troubleshooting regime and we’re not talking about last resort things here we’re talking about one of the first options.

    If it was so bad Apple wouldn’t recommend it until the very last resort when everything’s gone pear-shaped.

    As for this suggestion it seems to work perfectly for me. I tested it using Bento which the the app I use the most on my iPhone and given the large amount of data it was a hell of a lot quicker than just after the upgrade.

  • ShabbaRanks

    I don’t suppose anyone else is getting problems with the calendar app? I’m getting disappearing entries and it won’t let me add new ones over where the old one was to fix it. MobileMe, not exchange.

  • marlowe

    @ShabbaRanks: you probably have inconsistent sync data with mobileme. You can get free support online if you go to apple.com/support and on the left hand side select MobileMe from the drop down menu. Then scroll to the bottom and select troubleshooting sync issues and keep clicking on things until a “chat with MobileMe rep” comes up.
    As far as my earlier comment I posted I still stand by it. @lowededwookie you’re right that my recommendation is more of an “all else fails” effort but the title of the article/discussion is how to speed up your 3G and this will do it better than anything else recommended here. Let’s be honest the 3G’s processor and memory are lacking when it comes to running the iOS 4 software efficiently. You want it running as clean as possible and the way to do this is by restoring the phone in iTunes, setting it up as a new phone, and SYNCING your data back to the phone. I’ve personally never seen any official Apple documentation recommending this hard reset to speed up the iphone’s OS. I’ll be honest I don’t know much at all about the inner workings of the iOS 4 software but I do know from experience that forcing a hard reset on the iPhone is a way of getting things working when they were not but it is not a magic clean up. The hard reset is a 2nd or 3rd step in the troubleshooting process. However, if you want to optimize the iPhone 3G with iOS 4 then give the steps i listed above a shot.

  • http://www.lowededwookie.com lowededwookie


    Nope, because I did that when I upgraded and it caused it to be slow.

    The method Dan shows actually made it work better not the one you’re suggesting.

    Anyway, getting an iPhone 4 when it gets released here in New Zealand soon… whenever soon may be.

  • ShabbaRanks

    @ Marlowe,

    Thanks for the info. Fortunately I don’t require support for it as I’ve enough expertise to rectify it myself. The info was useful though.
    I was just wondering if anyone here had had an issue with the cal app, that’s all.

  • travelbyphone

    My solution has been to close all Safari tabs before quitting it and today I found out that clearing the safari cache also helps.

  • ShabbaRanks

    To quote Stephen Fry:
    “At the extremes humans can love or hate. I have raved, screamed, shrieked and cursed when my iPhones, Macs, iPods, Airport base units and Apple TVs have betrayed me, let me down. I expect so much of them. But it is nothing to the venomous fury, disbelieving rage and overmastering contempt that floods my being when attempting to get function, sense and use out of a Windows, especially a Vista machine.”

  • Microphobe

    I love visiting here for the substantiated insights and the respectful, spirited comments! I feel a real sense of community and I just wanted to add my findings after trying Daniel’s suggested procedure.

    I have an iPhone 3Gs 16GB with 74 apps and 10.8GB free. I didn’t use a stopwatch but pressing and holding [Home] + [Sleep] seemed to initiate the process in fewer than ten seconds – more likely 4-5 secs. My 3Gs was up and running again very quickly: about 20 seconds.

    I tried the rebuild due to one specific app: textfree by Pinger. Pre-rebuild scrolling through message threads was lethargic. I had to press and *hold briefly* then start sliding to initiate a scroll. After the rebuild scrolling is definitely more responsive (flicking the screen works again) but still slightly balky.

    I have zero familiarity with the internal workings of iOS but thought I’d mention: remember to Sync before attempting any troubleshooting! Better safe than sorry, right? :-)

  • alaskan

    First background on my iphone, I have a 3Gs with 32GB. I am using just under half of the 32GB of space availible. (Apps, music, etc) Prior to upgrading to iOS4 my phone worked fine with no issues. After upgrading to iOS4 my phone has been buggy and laggy to the point of crashing when using every app (this includes apples apps mind you!) at least once per day. I have done both soft and hard reboots. I wiped and then reloaded the OS all to no avail. I have over 20+ years in the IT field as well as troubleshooting /electronics and programming experience so I’m no noob when it comes to knowing my way around devices and how to fix them or their OS’s..
    I downgraded the phone to the previous release OS3.1 and have gone back to having no issues with the phone.
    Until apple gets their act together and releases a fix for OS4 I’ll stick with the previous release. I wont bother saying I expected better because honestly I didn’t. Apple is no better than any other company out there, they are releasing subpar software and equipment just like the rest. The OS was probably coded in Chinia to boot..

  • nishkabob

    Thanks for the suggestion… I force-restarted, and things did run a bit faster for a while, but gradually became glacial again. I would tap the screen and wait 5-10 seconds for anything to happen, so I just downgraded back to 3.1.3. Ah well, time for an iPhone 4…

  • mihomeagent

    I don’t note any improvement. And I did note a sharp degradation when I upgraded. Which I kind of wish I had not done. Can I go back?

  • http://Www.bitburn.org bitburn

    Go back you can indeed. Follow the link below. I did and rolled back to 3.1.3.


  • ShabbaRanks

    Slightly off topic but yesterdays Apple press conference about was much more the behaviour I expect from Apple. They explained the issues well, pointed out why they consider it to be a minor issue at best and are going out of their way to provide cases for iPhone 4 users when they really don’t have to.
    This kind of reply to “controversy” is what Apple should be doing, not banging out one sentence emails about how people are over-reacting.
    I was unlucky enough to be watching the cnet feed of the conflab and saw, live, that the “journalists” there were really disappointed that Apple had only announced free cases and not a recall and redesign. They were also strangely preoccupied with how Apple “needs them” as tech journos.
    Watching that feed made me realise that this antenna furore is manufactured specifically to put Apple in it’s place. Tech journos are prepared to kill their own grannies to push Apple to announce a redesign and recall. Even the BBC are getting in on the act which disappointed me. Their recent interest peice on how to return your mobile phone was obvious and depressing.
    The issue is obviously real but there’s no way it’s affecting as many people as the media are making out.
    Quick tip Steve: Journos/Saddos are sending you email to get a rise out of you and then publish it on their shitty blog. Be slightly more careful with what you’re emailing out.

    Anyway.. Had to get that out of my system.

  • http://wanderbook.com eddieclay

    This whole iOS 4 thing on my 3G, its Apple’s Vista.

  • http://wanderbook.com eddieclay

    After a full restore as a new phone: has been working like new for a week.

  • jaron

    This helped my 3G a lot. Thanks!!

    I was in the habit of shutting the phone off once every day (just holding down the top button and sliding to shut it down, then starting it up again) before the iOS4 upgrade, which seemed to keep it speedy, but that wasn’t effective anymore after the upgrade.

    Doing the hard reset once, and turning off a bunch of Spotlight search options helped a ton, but it degraded again after a few days. Shutting off / on again seems to have helped again today.

    So for me, the one hard reset seems to have done the trick, but the off / on habit every day also seems necessary.

    My 16GB 3G is still noticeably slower than a friend’s 32GB 3G. He has way fewer Apps, and all his are free (arguably less intensive than many of mine).

  • airmanchairman

    Sorry Daniel / People, couldn’t wait for this article to be revisited in the wake of iOS4.1 being made available.

    My 3G, which I was well-pleased with even after the 4.0 upgrade, just got even better. Runs much faster, crisper and snappier after the 15 – 20 minute upgrade.

    As a plus, my Plantronics Voyager 855 Stereo bluetooth headset just acquired the (full) AVRCP feature of NEXT / PREVIOUS selection via the Volume up / Down buttons, and I am over the moon!