Im having the same issue.
Here are the things I noticed:
1) home screen with icons seems faster when swiping left/right
2) lock screen is slower then swiping the lock slide to the right. its jumpy
3) SMS app is slower especially when sending a message, the text-bubble doesn't smoothly animate to go to the sms thread. it just jumps to there with no transition. (its probably because of the new spell checker which uses additional RAM)
4) the Settings page is really sluggish. doesn't respond right away on clicks and swipe (down/up).
5) opening an app (Photos for example) makes it look like its loading faster because you see the albums right away.. but actually it only shows the after-image when you last access it while its still loading Photos in the background. They use the after-image technique just to make it appear that its loading faster.
6) loading maps has good fade-in transition now unlike before.
7) Camera really improved! i noticed that its less blurry when you're focusing something near. brightness in dark light has improved too.
8) the Notepad icon looks crumpled just below the brown bar.
9) iBooks is sooo slow... turning pages doesn't respond sometimes.
10) Some of my apps are now really slow.
11) normally, when i press the sleep button, ill hear a clicking sound with the push. but now, the clicking sound is really delayed. same thing when slide-unlocking the device.
12) iPod sound seems lower now... i have a fixed volume setting in my car and i know how loud it sounds coz i listen to it every single day with my iphone... but now the sound seems lower with the same exact volume setting in my car and in the iPhone volume. equalizer setting in car and iPhone are exactly the same too...
13) all my songs in my iPhone has lyrics on it (i put them one by one), and now they're gone!!! although the album art are still there...
i can go all day...
i just wish there's an option to disable features you dont need which may be eating memory resource like landscape keyboard, spotlight search, the new spellcheck, etc). i think when those are disabled, it would make iPhone 3G back to being smooth and fluid like in the old iOS 2.0 days...
I was having similar issues after upgrade. I had similar problems before after one of the previous updates and the solution there worked here as well:
1) perform backup using iTunes
2) perform restore using iTunes
3) reload/resync music, videos, playlists
After this, the response of my 3G became quite snappy and animations smoothed out.
Kinda a pain to go through the process, but it works.
I can confirm what exq0867 is saying. I ran an "update" on my iphone 3g and it slowed way down. It bogged down constantly. I was still usable, but not at all pleasant, since it use to be much snappier. I read a few placed to try and "restore" my phone, and it worked. Now I don't notice much difference between 3.1.3 and 4.0. 4.0 is probably still a little bit slower due to the increase in the operating system size, but not enough to notice and cause great aggregation.
I was skeptical at first since I thought that an update basically did the same thing as a restore on the iphone, but apparently not. My only guess is that an update works somethings like a linux update where some libraries and other system files that are shared are left, unneeded ones are deleted, and new ones are put on, leaving the operating system bloated. A "Restore" completely cleans off the iphone, and installs only the new operating system leaving only what was designed to be there instead of a merging of two operating systems. Then you can use a backup to put all of your music, apps, etc back just as they were. The concept of how apple does their updates sounds a little sketchy to me (and I'm the one who wrote it, but its my only guess), but fact stands; my iphone was much faster after a "restore" compared to the "update."
I've tried the restore function and the system is still really sluggish. Especially the calendar - where the individual entries dissappear for 1-2 seconds after I open the app - and the SMS messaging app. Unfortunately these are 2 of my most commonly used apps.
When doing the restore, do you select the 'restore from last backup' option or the other total (factory) reinstall of the software?
I am thinking of doing the total reinstall and then the backup restore. Is this what you did?
I tried the backup and the restore and nothing is restoring the fluidity of my iPhone from two days ago. I tried calling the tech support and they told me there is nothing we can do to revert back to the older operating system. My phone is so slow and at night suffers from "sundowners" disease and seems to function even worse. If this is Apple's way of getting us to buy a new phone, it's just turning me off from the product. I'm about over AT&T as well and when my contract is up, I might check out what phones are available at Verizon. It doesn't matter how much you love Apple products when you constantly get kicked off conference calls as a freelancer.
Apple needs to get off it's simplicity high horse and either fix OS4 or give us the option to downgrade to the older operating system.
This is absolutely ridiculous, the additions to the 3G handset are consolidation of email, a zoom to the camera and folders on the homepage....so why the **** has the handset slowed to snails pace??!
I understand apple runs a business but c'mon!
IOS4 is clearly not intended as a software upgrade for the 3G as the drawbacks outweigh the benefits.
One can only imagine that this is intended to more clearly define the differences between the 3g, 3gs and the 4. Doing this through software is the wrong way to go about it.
This is absolutely ridiculous, the additions to the 3G handset are consolidation of email, a zoom to the camera and folders on the homepage....so why the ** has the handset slowed to snails pace??!
Guess ill live without combined email inbox, useless digital zoom & folders.
For me, just not worth my phone slowing down to crawling pace. Not to mention the insane battery draining & gps problems.
Feel so glad I managed to revert back to 3.1.3
Message was edited by: iWUB
My brother has a 3G that's much slower now with OS4. He called Apple tech support to ask if there was a way to revert back. The girl he talked to actually told him that was not really, maybe he could jailbreak the phone. We had a good laugh at that.
P.S. - it is possible to downgrade your OS, but it does not involve jailbreaking, and it is a pain in the rear.
My iPhone 3G was working sMoothly and with almost no delays.
Now after iO4 it has slowed to treacle speed
5 seconds to open the text window
another 3 seconds to get a popup text input keyboard
3 seconds to open the email window
Much longer delays for other changes
Someone above mentions iOS4 as a beta .... that is not what it said when iTunes wanted to update it !