You update your iPhone, and within a day it feels slower. It runs warm in your hand. The battery, which used to see you through to bedtime, gives up at teatime. Somebody in the family says the words out loud: “time for a new one, then.”
Usually it isn't. A phone that feels slow after an update is one of the most fixable problems there is, and the fix is nearly always free. Sometimes it's a battery, which costs a fraction of a new handset. Occasionally the phone really is finished, and we'll tell you how to spot that too.
This is our honest position: you should not have to buy a new phone every two or three years. The upgrade cycle is a habit the industry sells you, not a law of nature. Here's what actually happens after an update, what to change, what to ignore, and when to stop spending money on a phone that's genuinely past it.
First: wait a week before you judge it
This is the single most useful thing on the page, and it costs nothing. When a big update lands, your phone doesn't just install it and stop. It spends the next few days re-indexing: rebuilding the search index, working through your photo library, and downloading and updating apps in the background. All of that uses the processor, which uses battery and makes the phone warm.
Apple says it plainly. On its own page about batteries draining too quickly: “If you notice that your battery life has decreased after updating your device, wait a few days and then check again.” And on its page about a device getting too hot, Apple lists the situations where feeling warmer is normal, including when you “complete a software update, particularly to a major release”, adding that “your device will cool when the process has finished”.
So the first step is patience. Give it a week of ordinary use, keep it charged, and then look again. A good number of people who replace a phone in the fortnight after a big update are replacing a phone that was about to go back to normal by itself.
You can watch this happening. Open Settings and tap Battery. Apple's daily usage chart shows which apps have used the most battery, and tapping View All Battery Usage gives you the full list. If the big users are system items rather than the apps you actually opened, that's the post-update work showing up.
Which iPhones get iOS 26 at all
Apple's own compatibility list for iOS 26 covers the iPhone 11 and later, plus the iPhone SE (2nd generation) and iPhone SE (3rd generation). So a phone from 2019 is still getting the current version of iOS, which is worth remembering next time someone tells you a five-year-old phone is obsolete.
The catch is that the oldest phones on that list are being asked to draw a much fancier interface than the one they shipped with. Which brings us to the next bit.
Turn down the new look
iOS 26 introduced what Apple calls Liquid Glass. In Apple's own words from its announcement, it's a “translucent material” that “reflects and refracts its surroundings” across controls, navigation, app icons and widgets. It looks lovely. It is also more work for the phone to draw than a flat panel of colour, every time you swipe.
You don't have to put up with it. Two settings that Apple provides for accessibility reasons will calm the whole interface down:
- Settings › Accessibility › Display & Text Size › Reduce Transparency. Apple describes it as “improves contrast by reducing transparency and blurs on some backgrounds”. Menus and panels become solid instead of frosted.
- Settings › Accessibility › Motion › Reduce Motion. Screen changes use a simple dissolve rather than zooming and sliding, the parallax effect where icons drift as you tilt the phone is switched off, and animations in some apps stop.
Plenty of people leave both on permanently, and not for performance: less motion is easier on the eyes, and solid menus are easier to read. If your eyes are tired by the evening, try them for a week.
Then check the battery, not the phone
A battery is a consumable part, like tyres. It wears out on a schedule of its own while the rest of the phone is still fine, and it is the single most common reason an older phone feels slow, because iOS deliberately eases off when a battery can no longer deliver the power the processor asks for.
Go to Settings › Battery and look at Battery Health. Two numbers matter:
- Maximum Capacity. Apple defines it as “the device battery capacity in relation to when it was new”. 100% is a new battery. 79% means you have roughly four fifths of the running time you started with.
- Peak Performance Capability. This is the battery's ability to deliver power in a hurry. Apple says that when a battery can't, iOS “will dynamically manage the maximum performance of some system components, such as the CPU and GPU”, judged on temperature, charge level and the battery's internal resistance. That management is what “my phone got slower” usually means in practice.
What counts as worn out? Apple designs batteries in the iPhone 14 and earlier to keep 80% of their original capacity after 500 full charge cycles, and iPhone 15 models to manage the same 80% after 1,000 cycles. Which? puts the practical line in the same place: 80% or above is healthy, and a battery should hold that for at least 800 full charges.
Below 80%, a new battery is the answer, not a new phone. Which? reported in August 2026 that Apple charges roughly £95 to replace an iPhone 17 battery, and that independent repair shops charge around £70 to £100. Set that against several hundred pounds for a new handset. If you have AppleCare+, Apple replaces the battery at no extra charge once capacity drops below 80%, so check before you pay.
The settings that genuinely help
These are the ones worth changing, in the order we'd do them. Two of them cut down how much your phone reports about you as well, which is our usual territory.
Background App Refresh
Settings › General › Background App Refresh. This lets apps wake up and fetch new content while you're not using them. You can switch it off for everything, or better, go down the list and leave it on only for the handful where it matters. Most social and shopping apps do not need it.
The privacy bonus: an app that can't wake up in the background can't report in while it's in your pocket.
Location Services
Settings › Privacy & Security › Location Services. Work through the list and change anything set to Always down to While Using the App, or to Never for apps with no business knowing where you are. While you're in each app, turn off Precise Location unless it genuinely needs your exact position, a weather app doesn't.
The privacy bonus: this is the biggest single win on the page for reducing what leaves your phone, and it saves battery, because GPS is expensive to run.
Low Power Mode
Settings › Battery › Power Mode, then turn on Low Power Mode. Apple says it works by “reducing or disabling certain settings and features, such as Mail fetch, Hey Siri, Background App Refresh and some visual effects”. You can leave it on all the time if you like; the phone still works normally for calls, messages, maps and the camera.
Screen brightness and auto-lock
The screen is the hungriest part of a phone. Apple's own battery advice flags high brightness as a big drain. Turn brightness down a notch or two, or leave it on automatic, and set Settings › Display & Brightness › Auto-Lock to 30 seconds or a minute so a phone left face-up on the table isn't lighting up the room.
Automatic downloads
App updates and downloads landing while you're out use both data and battery. You can keep automatic app updates (they matter for security) and still restrict them to Wi-Fi, which is the sensible middle. Our one hour phone spring clean walks through this and the app permissions tidy-up in more detail.
The myths, including the big one
Closing your apps does nothing. This is the most widely believed piece of phone folklore there is, and Apple contradicts it on its own support page: “You should only close an app if it's unresponsive” and “closing all of your apps does not impact your device's overall performance”. Apps in the switcher are parked, not running. Swiping them all away every night achieves nothing except making them slower to open next time.
Cleaner and booster apps. There is nothing for them to clean. Apple's own security documentation says every third party app is “sandboxed”, which is “designed to prevent apps from gathering or modifying information stored by other apps” (Apple Platform Security). An app cannot clear another app's files, so anything promising to free up memory or speed up your phone is selling you a placebo, usually with adverts and data collection attached. The genuine version of that job is Apple's own storage screen, further down this page.
“Battery calibration” apps. Same story. Draining the battery to zero and charging it back to full doesn't recalibrate anything on a modern iPhone, and running it flat isn't doing the battery any favours: Apple's own advice for storing an iPhone long term is to leave it half charged, not empty.
Turning everything off at once. Tempting, but you end up with a phone that doesn't notify you about anything and you still don't know which change helped. Do two or three things, use it for a week, then decide.
When it really is the hardware
Honesty cuts both ways, so here are the four cases where settings won't save it.
- Storage nearly full. A phone with almost no free space has nowhere to work. Check Settings › General › iPhone Storage: available space is at the top, and underneath, Apple offers recommendations and the option to offload apps, which frees the app's space while keeping your documents and data. Videos and photos are usually the culprits.
- A battery below 80%. Covered above. Replace it, and the phone often feels new again.
- A swollen battery. If the screen or the back panel is lifting, or there's a visible bulge, stop. London Fire Brigade's advice on lithium batteries that swell is to “stop charging immediately”, “turn off the device”, “do not remove the casing or tamper with the equipment” and “contact the manufacturer or certified technician”. That is a repair job today, not next month.
- No more security updates. This is the one that genuinely ends a phone's life, and it's about safety rather than speed. If your model has dropped off Apple's compatibility list for the current version of iOS, the monthly repairs stop coming. Apple publishes which models each new version of iOS supports, rather than a support end date years ahead, so the practical test is whether your phone is still offered the newest iOS. Our guide to how long a Pixel gets updates explains the Android side, where the dates are published years ahead.
One more, while we're here: a phone that's suddenly hot, flat and slow with no update to blame might have something running that you didn't install. That's rare, and the real signs are specific. We went through them in how to tell if your phone has been hacked.
The money, and the waste
Put the two options side by side. A battery is about £95 from Apple, or £70 to £100 from an independent shop, plus an afternoon of the settings above. A new mid-range phone is several hundred. The battery wins outright unless the phone has stopped getting updates.
There's the other cost too. Every phone replaced early is a phone's worth of mining, manufacturing and shipping brought forward, and a working device sent for recycling. If you do buy new, UK rules are on your side for getting rid of the old one: under the electrical waste regulations, a retailer selling you a new item must “provide a way for your customers to dispose of their old household electrical and electronic equipment when you sell them a new version of the same item”, whether you bought in a shop or online.
Wipe it before it leaves the house. Apple's steps are: back it up, unpair an Apple Watch, sign out of your Apple Account (Settings, tap your name, scroll down, tap Sign Out), then Settings › General › Transfer or Reset iPhone › Erase All Content and Settings. Passing on a phone with your accounts still signed in is how people lose photos and get into arguments with strangers.
The honest summary
- Give it a week after a big update before deciding anything.
- Reduce Transparency and Reduce Motion cost nothing and help most on older models.
- Background App Refresh and Location Services save battery and cut tracking at the same time.
- Check Battery Health. Below 80%, buy a battery, not a phone.
- Ignore cleaner apps, and stop swiping your apps closed.
- The only thing that really ends a phone is the end of security updates.
And if what's actually bothering you is how much your phone reports back rather than how fast it is, that's the whole reason this site exists. Our free de-Google guide shows you how to take a Pixel off Google's tracking yourself, for nothing. An older phone with a fresh battery and the tracking turned off is a better machine than a brand new one reporting your day back to head office.