iPhone Slow After iOS 4.2.1 Update; Fixes

Some users have reported poor performance after the update to iOS 4.2.1. These users report delays in opening apps, switching between apps. They also report that the keyboard is slow to appear when beginning to enter text.


Perform a “hard reset.” Hold down the sleep/wake and home buttons simultaneously for roughly 15-20 seconds, until the screen powers off then an Apple logo appears, which signifies a reboot. Some users have (oddly enough) reported that performing two hard resets resolves the slowness issue.

Restore, but not from backup. It appears that bad holdover data from iPhone backups can cause performance problems. Restoring as a new phone will delete contacts and other data, but may resolve this issue.

To do so, connect your iPhone or iPod touch to your computer, click “Restore” in iTunes, then choose “setup as new phone.”

Free up space. Make sure that your iPhone has at least 10% of its available memory free. OS X-based systems, such as iOS 4.0, may require some free space to operate properly.

Close open Safari windows. One iOS application that consumes memory in the background is Safari. Close all unused windows in the application by pressing the page switch button in the lower right portion of the screen then clicking the X at the top left of each page. See this page for screenshots.

Turn off Spotlight. Navigate to Settings -> General -> Home Button -> Spotlight Search and turn off all the options by tapping each one. Next, perform a hard reset by holding down the sleep/wake and home buttons simultaneously for roughly 15-20 seconds, until the screen powers off then an Apple logo appears, which signifies a reboot.

You can experiment with turning off only some options, but most users only report a meaningful speed boost if all options are turned off.

Turn off MMS. Navigate to Settings > Messages > MMS messaging and slide MMS Messaging to “Off,” then perform a hard reset as described above.

DFU Restore. A tedious process, but one that has yielded dramatic performance improvements for some users.

To perform a DFU restore, follow these steps:

1. Backup your phone and preserve data. Follow the steps in this Apple Knowledge Base article to transfer your purchases and backup your iPhone.

2. Put iPhone into DFU mode. Connect your iPhone to your computer and open iTunes (if it doesn’t open automatically). Hold down both the top (sleep/wake) and home buttons for exactly 10 seconds, then release the top (sleep/wake) button but keep holding the home button until  iTunes displays a message stating that a phone in recovery mode has been discovered.

3. Restore. Press the restore button and allow the phone to complete the restoration data. After it is done, select setup as a new phone.

4. Restore your backup (optional). Next, you can restore the phone again in the normal fashion (not DFU mode) using the most recent backup rather than setting up as a new phone. However, this may cause the original problem to return in some cases. If the problem returns, follow steps 1-3 again and do not restore your backup.


  1. says

    I’m running a 4 week old 3GS (old phone was replaced due to a slack silent slider) and I suffered a loss in performance. The new one wad actually worse than the original one. My main issue was with multitasking, and a hard reset seems to have cured it nicely. Not much help to those that are still suffering, but worth mentioning.

  2. Rick says

    This is totally unacceptable….Apple should have known that upgrading to the new system would cause problems for 3G phones and given us a warning at the very least! These “fixes” haven’t worked and I’m pissed. The girl at the apple store was sympathetic and agreed that the older phones weren’t designed to work on the new system and that I couldn’t go back to the old system, and the only thing I can do is “restart my phone 2 or 3 times a day”…What a load of crap!
    Android is looking better all the time.

  3. says

    Still jamming, aborting apps, and slow after 4.2.1 update and recommended fixes. Here’s my suggestion, how about an update that restores it back to the way it was before the 4.0 update. Release the anxiety issues the Apple execs have about jail-breaking, lack of interest in upgrading units, etc. If this update (update reversal) is not seriously considered for us 3G(S) users, why stick with it, we feel we’ve been taken. We’ve seen how efficient and enjoyable the iphone can be and use to be, any delay comes across as a front, which is arrogant and is not appreciated. Thank You

  4. says

    3G phone is incredibly slow. Went to Apple Store tonight. Salesman said he would have never recommended an upgrade to 4.2.1. Had me meet with Tech. Tech said the same thing. Asked what I could do about it and the Tech said nothing. You cannot downgrade to an earlier system. I used to be able to get my USA Today App almost immediately. Now it is so painfully slow that I really can’t use it. So much for Apple. People swear by it others swear at it. I too am thinking about Android. Buddy has one and swears by it.

  5. Jimmy says

    I have a 3G. After the upgrade, my phone has been painfully slow to do the most basic tasks (texting, writing notes etc.) There is no way that Apple did not know this would slow down the 3G and 3GS. Apple thinks: “Hmm, if the 3G and 3GS phones suddenly lack in performance to the point where they are extremely inefficient, the customers will upgrade to an Iphone 4=more profits for us.”

    I think I will be getting an Android.

  6. Steve says

    This worked to speed up my iPhone 3GS

    Settings -> General -> Reset -> Reset Location Warnings


    Settings -> General -> Location Services (turn this off)


    Hard Reset (Hold sleep/wake and home buttons simultaneously until Apple logo appears – about 10 to 15 seconds)

    Result: Phone much faster, no problems typing in text boxes in Google maps, contacts or the Quick search feature.

    I can confirm that as soon as I turned on Location services and allowed Google Maps to use my location, there were significant delays in typing in Google Maps, Contacts App was scrolling jerkily, and the quick search feature was slow to respond to keyboard input and didn’t show any results (I got impatient and left quick search before any search results showed). Turned off location services and everything was quick again.

    Gutted I can’t use maps without a slowdown!

  7. duke says


    there is a way to downgrade to an earlier system. It worked for me. iPhone 3G from 4.2.1 -> 3.1.3.

    Let me know, if anyone is interested in.


  8. Christine says

    Hard reboot did the trick for me on my 3g.

    I was at the ATT store today looking at the 4G or an android phone. The sales guy told me there was nothing i could do to fix my phone after 4.2.1 made it ridiculously slow. My GPS was crashing every time I opened it. I am so glad I didn’t pull the trigger on a new phone today and came home and googled my problem. I’m sure the ATT sales guy knew about this potential fix and didn’t tell me in the interest of sales. F him!

    You saved me $200 today! Thank You!!!

  9. Patrick says

    Guys Im using Iphone 3G 16gb. Was so shitty slow on 4.2 so i downgraded to newest 3.v ( it is possible) and I experienced bloody great performance upgrades.Downgrading was a medium hard process but it is doable i used youtube guides. Pretty much go for androids because Apple are useless bastards.

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