Iphone 3G slow after update to IOS4

ME TOO!!!! every since i upgraded to iOS4, my iPhone has been extremely sluggish, slow, and glitchy. What's going on? THIS *****!!!!!

I had the same problems.
Last night i downgraded to 3.1.3 again!
This is so much better and faster.

You need to restore your 3G with iTunes (not 9.2, you need an older version) in DFÜ mode.
After that you get an error ( mine was 1015error).
Thats fine. Then you have to reboot your phone with RecBoot.

Thats it...

I have a theory about what's going on here.

When I first got my iPhone 3G, it was very snappy. Then I loaded it almost full with music and video, and it slowed to a crawl. It's never been the same since. Removing the media didn't help much, and even a full system restore didn't help any further.

As you know the iPhone 3G has only 128MB of DRAM. When that's not enough, like any modern OS, it swaps pages to "disk", that disk being the flash drive (16GB in my case).

My theory is that with so little free space, the wear leveling was confined to a small space, the logical to physical sector mapping got fragmented, and as a result, write performance got very poor. Removing the media helped because it allowed the wear-leveling algorithm to use more of the disk when writing to swap, but nevertheless it continued to get more and more fragmented over time. Restoring to factory settings doesn't help because the logical/physical mapping is managed in the drive, and that isn't reset when you restore the device.

With iOS4, the pressure to swap pages to/from disk is even greater, causing even greater and accumulating fragmented disk blocks. The result is very poor write performance that gets progressively poorer.

The fact is, the iPhone 3G just doesn't have enough DRAM for the new OS. And Apple has failed to do something really fundamental to help with this, which is to do background defragmentation of the solid-state drive.

The reason that newer devices with 256MB+ of DRAM don't have this problem is because swap pressure is dramatically reduced. Regular app performance isn't affected so much because reads are still fast, although even they should notice gradual slow-down of apps that do a lot of writing to the drive (which fortunately doesn't happen all that much).

Yep, my 3G has slowed down so significantly it has really become a pain to use. Will try a restore and se what happens.

Mine was horribly slow too. Unusable really. I was able to fix it - directions here: http://discussions.apple.com/thread.jspa?threadID=2478473&tstart=0

I too had the same issue but I dont think you have to go through all of that, most non-apple(except iphone) users do not know tricks for the apple products.

The reset trick seems to have fixed my speed/lag issues, which were pretty bad, I would reply to a text then I would hear my phone receive their reply text without mine being sent.

The simple reset was pointed out earlier, just hold down the top and home buttons until the apple appears, after it comes back(it will take a few minutes, be patient) the phone will be faster. At least that fixed my issue, I was shocked when I talked to apple support yesterday when they acted like there was no reports of the phones being slow, all I had to do was google it and found a ton of people that were upset.

ya same here i tried hard reset and restoring for an earlier backup and as a new phone when i set it up as a new phone it killed my battery so bad to where it will only last an hour until it dies i called and they also acted as if nothing was wrong with their phones and say they could not help me and now im gonna take it in a local apple store and see whats happening

Try doing two "hard resets" to your phones.

http://www.cultofmac.com/speed-up-iphone-3g-ios4-with-a-hard-reset/48070

Got it from there, worked great. I'm still trying some things but so far after doing that my phone is now fast and speedy like it used to be 🙂

I'm having same issues and its not just slow and lagy for me, my 3G is not even working. I cant upload anything on my 3G. WiFi works so i don't get whats wrong with the 3G. This is bull crap. Apple just messed it up. Thanks A LOT APPLE!

I tried to update to OS4 and now my phone is frozen in the emergency only call screen with itunes and the picture of the USB connector. What do I do now? help....

My upgrade took around 3 hours, and it went ok
but iOS4 is a crappy upgrade for my iPhone 3G .. it's SLOW !!!! I can't seep the finger to answer a call, cause it now looks like those chinese fakes HIPhones. . it's not as smooth as it used to be, it's not responding properly, sometimes the contact list just freezes in a name, and I can't go back . have to turn the phone off ... well ... not a very good move apple .... I'm going back to version 3 of the system ;-(((((( not a happy user ..!!!!

+ 1 on all the comments posted here.

I have also noticed Apple apps crashing a lot more than usual: Phone, Calendar, Photos, etc. Some won't open at all until the 3rd or 4th try.

I will try the hard reset once the phone recharges. Only lasted 2 hours after the upgrade.

Still no way to sort emails? Come on, really guys?

Sounds like iOS4.1 is well overdue already....

Thank you Apple!

My two year old, perfectly good iPhone 3G has been transformed into a sluggish, diificult to use, frustrating piece of kit! All thanks to iOS4!!!!!!!

I've gained nothing, apart from the above! Oh, did I forget to mention it now locks up while in apps, freezes whilst on the Internet and sending a text is now painful!

If you spot any spelling mistakes, that's because the qwerty kyboard now locks up when typing and misses out letters!!!!

Sorry for the rant Apple, but my trusted 3G is no longer my best friend!!!!

Unless you can fix it please!!!!!!!

Surely Apple is some how liable here!!!!

Is this deliberate? Forcing us into new phones and contracts!!

Same problem here: slow 3G. Restore to factory settings and "hard resets" doesn't improve speed. Especially the 'unlock-slider', sliding app pages and using Calender feel slow.