Apple's iPhone 5 is its flagship smartphone, but older models remain popular: the iPhone 4S and iPhone 4 are still sold by Apple as budget alternatives, and plenty of Apple fans continue to use a beloved iPhone 3GS or even older iPhone.
But is your iPhone 4 or 3GS still performing? All computing devices are prone to slowing down over time, as their memory fills up and extra software is installed, but the way iPhones use their memory makes them less prone to this than most.
It's possible that it just feels slower than it used to, because you've got used to what initially seemed dazzlingly quick operation, or have started to compare it to friends' newer, faster models.
But sometimes it's possible to make a direct comparison: when there's an app you used to enjoy but has since become unusably juddery. Such a situation is what led us to write this feature. The wonderful, super-fast game Super Hexagon demands lightning reflexes to survive, but the stuttering graphics on our iPhone 4 now make it impossible to play. We've also been seeing problems with the iPhone 4 handling Temple Run 2.
Here are some great methods to speed up an iPhone 3GS, iPhone 4, iPhone 4S or even iPhone 5, if you're not happy with the way it's running.
Shut down all open applications
Let's start with the easiest solution: closing down all non-essential apps. The way multitasking is handled (or rather not handled) in iOS 6 means they shouldn't be hogging the RAM to any significant extent, but it can't hurt.
Double-click the Home button to bring up the tray of currently running apps along the bottom of the screen. Press and hold any of these icons until they all start wobbling, then start pressing the red minus signs to close them down. We've going to close down everything, then start again from scratch.
Clear your Safari cookies and data
Let's try emptying Safari's data, cookies and so on to free up some memory.
Open the Settings app and scroll down to Safari (it's the last in the fourth set of options). Here you can choose Clear History and Clear Cookies and Data. (Bear in mind, though, that Safari will no longer suggest URLs as you type, unless they're bookmarked. And clearing the data may mean some websites forget your preferences.)
Let's restart the iPhone completely. Press and hold the Sleep button (the one on the top right of the iPhone) until the Power Off slider appears. Swipe it and wait for the iPhone to power down.
Once it's finished (it'll take about 10 seconds or so), start the iPhone up again by pressing and holding the Sleep button for about 5 seconds. You'll see the apple icon for a minute or so, then the iPhone will restart.
Delete text messages
We'll continue on our quest to free up memory by going through the Messages app and deleting everything that we don't need to save.
Open Messages and scroll down to find any message threads that you can manage without. Swipe to the right and tap Delete. Alternatively you can tap Edit and tap the red minus buttons to delete unwanted threads.
Delete unnecessary songs, photos and videos
Okay, let's get serious and free up a lot more memory. Open the Settings app, then tap General, and Usage. You'll see how much storage space is left and which apps are using up most of the space.
If you're anything like us, the top two culprits will be Music and Photos & Camera, because these apps' storage usage includes music, images and videos. Considering that we've only got 485MB free out of 16GB, it's worth trimming this down.
Open the Music app and find the non-vital track, album or artist that you want to delete. Swipe to the right and press Delete.
For photos and videos, we're going to plug the iPhone into our Mac and use the pre-installed app Image Capture. (For more on using this, see our article 'How to transfer photos from your iPhone to Mac'.) This will allow us to copy the photos we want to keep on to the Mac for safekeeping and backup, and delete them from the iPhone.
Plug the iPhone into the Mac and open Image Capture (assuming you've not set it to open automatically when it detects an iOS device). Tick the option 'Delete after import' at the bottom left.
Click the photo you want to copy across, or select multiple consecutive photos using the Shift key, and drag and drop them into a folder on the Mac. You'll see a green tick appear next to them in Image Capture, to show that they've been downloaded.
If there are any photos on there that you don't want to keep but still want deleted from the iPhone, select them and click the red circle at the bottom. Image Capture will confirm you want to delete the photo.
Of course, you can also delete photos on the phone itself. Open the Photos app, find an image you want to delete and tap the bin icon at the bottom right. If the bin's not showing, tap the photo itself to bring up the various options.
Pruning our photos and music brings the available storage to 1.5GB.
Uninstall non-vital apps
Open up the Settings app again, then General, Usage. Music and Photos are still taking up a fair bit of space, but there are lots of other apps hogging memory. Let's get rid of some of them.
Scroll down and tap Show all Apps. You'll see the apps installed on the iPhone, arranged according to how much storage they're taking up. If you see one that can go, tap it and then press Delete App.
You can also delete apps from the home screen. Tap and hold an app icon until all the icons start wobbling, then tap the black cross and then confirm the deletion.
After pruning our apps we've got the available memory up to 3.3GB. Testing in Temple Run 2 to see if there's any effect, we find that while there's still some stuttering, it's by no means unplayable.
A more drastic step than restarting the iPhone, a full reset takes longer but is a more effective way of solving problems with the way an iPhone is running.
Press and hold the Home and Sleep buttons at the same time. Keep holding them while the screen goes black (the red power-off slider may appear; if it does, just carry on holding the buttons), right up until the silver Apple logo appears. When that appears you can let go.
Things now appear much improved in Temple Run 2. In a 2km run, we saw only one very slight stutter, and gameplay was fine. Are we finally making some progress? Super Hexagon too runs without any problems at all. That's our iPhone 4 sorted, but what solutions would be left if you still weren't happy?
Restore from backup
The next stage after resetting the iPhone, getting steadily more drastic as we go, is restoring it from a backup.
If you've backed up recently, you can simply restore from that. Plug the iPhone into the Mac and open iTunes. Click the button where it says iPhone at that top right of the window (if you've plugged in more than one iOS device it may say '2 devices' or similar instead). Under Backups, click 'Restore Backup...'.
(To back up your iPhone into iTunes, click the Back Up Now button next door.)
Restore to factory settings
Finally, the most drastic step of all: we're going to perform a full restore, which deletes all the data on the iPhone and returns it, in effect, to the state it was in when you bought it. (Except that the hardware components will still have suffered a number of years of wear and tear, of course.)
Since we're deleting all the data, it's vitally important that you back up the iPhone: either back up to iTunes, as described above, or to iCloud. (To back up to iCloud, Open the Settings app, then scroll down to iCloud, then Storage & Backup, then Back Up Now.)
Now you can restore the iPhone to its factory settings by going to Settings, General, Reset, Erase All Content and Settings. You'll then have to enter your passcode if you've got one, and then confirm that you want to delete all media and data, and reset all settings.
After a few minutes of restoring, you'll be presented with the welcome screen you saw when you first started up the iPhone.
Check your warranty, and make an appointment with Apple
If none of the above techniques work, it's time to decide whether the speed of your iPhone is a serious enough problem for you to take it up with Apple. If there's a problem with a component, the issue may be covered by your Apple warranty if you have one - see 'Will Apple replace my iPhone?' for more on your legal rights.
However, as we mentioned above, slowness can be a matter of perception; but if you're sure something's up, and you've tried all our tricks, you may wish to ask Apple if they can check for a hardware issue.
The last resort: get a new iPhone
If Apple can't help, or their help is too expensive to be worth it, we reach the final option: give up on your older iPhone and buy something newer.