Why Your Phone Got Slow (And the 4 Fixes That Actually Work)

You are at the pharmacy counter with the app open, waiting on the barcode. The
screen stays white. The person behind you shifts their weight. Six seconds later the code finally
draws itself. That night you text your daughter and the keyboard runs a full word behind your thumbs
— letters landing after you moved past them.

Your phone is two years old, so you do the math everybody does: worn out, time to spend $900.

It is not worn out. Nothing inside grinds down like brake pads. Four things changed quietly,
and each is a setting you can put back tonight. Take them in this order — most likely first, not
biggest first. Nobody ranks what slows a phone down.

Step zero, iPhone only: the screen that names your symptom

Spend ten seconds on Settings → Battery → Battery
Health, in the section Peak Performance Capability.

As a battery ages, iOS manages the processor to prevent unexpected shutdowns — and Apple names the
visible result as longer app launch times and lower frame rates while scrolling. That is your
pharmacy counter and your lagging keyboard, in the manufacturer’s words. If that screen says
performance management has been applied, your problem is the battery — a fraction of the price
of a new phone.

Fix 1: get back above 20 percent free space

You have heard “never pass 90 percent full.” Neither company publishes that number. Android’s
source code publishes a real one: 20.

Above 20 percent free, Android sets aside 10 percent of your drive as cache room for your apps.
Below the low mark — 5 percent of the drive or 500 MB, whichever is smaller — that reserve drops to
2 percent, and in between the code shrinks it a little for every gigabyte you fill. On a 128 GB phone
that is about 13 GB of cache room while you still have 30 GB free, and about 7.5 GB once you are 90
percent full. Your apps spend the day rebuilding what the system threw out. The chip is not tired — the
operating system is squeezing it.

iPhone: Settings → General → iPhone
Storage, and give it a minute to count. Then set the switch that handles this forever:
Settings → Apps → App Store → Offload
Unused Apps. No fear needed: your iPhone removes the app but keeps its documents and data, the icon stays on your Home Screen with a small cloud, and tapping it reinstalls
the app.

Pixel and stock Android: Settings → Storage →
Free up space → Select files → Move files to
Trash. For autopilot, go back to the Free up space screen, tap
Settings there, and turn on Smart Storage.

Samsung: Settings → Battery and device care →
Storage, tap a category such as Images or Videos,
press and hold one file to start selecting — or tap All at the top of the screen —
then Delete all → Move to Trash. Samsung renames this menu often, so if
those words are missing, tap the magnifying glass in Settings and type
storage.

Fix 2: the apps still working while you are not looking

Every app refreshing itself in the background spends your battery and your data on your behalf,
whether or not you opened it. Trimming the list is a five-minute job.

iPhone: in Settings, under General, find
Background App Refresh and switch it off for the apps you open twice a month. Apple
frames this as a battery-and-data feature, not a speed feature — less competing for your charge.

Pixel and stock Android: Settings → Apps →
See all apps → tap the app → App battery usage → Allow
background usage. Google’s three settings, in its words: Unrestricted allows
all background work and might consume more battery; Optimized, the default, adjusts to how
you use the app; Restricted restricts background battery use, and some apps might not work
as expected and some notifications might be delayed. Restrict a messaging app and your texts arrive late, or never.

Samsung: One UI moves these controls between versions — tap the magnifying glass
in Settings and type background.

Fix 3: cache — Android can dump it, your iPhone cannot

Pixel and stock Android: Settings → Apps →
See all apps → tap the app → Storage & cache → Clear
cache. On Samsung: Settings → Apps → find the app →
Storage → Clear cache. Do your three heaviest apps and you are out in
two minutes. Google’s footnote: this deletes temporary data, and some apps may be slow the next
time you open them. That wears off.

iPhone: there is no system-wide clear-cache button. The only documented one is Safari’s: Settings → Apps → Safari →
Clear History and Website Data → pick a range → Clear History.
Apple notes it does not change your AutoFill information. For Instagram or TikTok there is no button
at all — deleting and reinstalling is the only route, so know that password first.

Fix 4: the update that has been sitting there since spring

iPhone: Settings → General → Software
Update → Download and Install. If it complains about space, tap
Continue: in Apple’s words, the system removes apps temporarily to make room and
reinstalls them automatically afterward. Then open Automatic Updates. The row
called iOS Updates, under the heading Automatically Install, is the
whole-new-version one. Security patches ride on a separate switch: on most iPhones it is the row named
Security Responses & System Files on that same screen; on the newest iOS it moved
to Settings → Privacy & Security → Background Security
Improvements → Automatically Install. Turn that one on and you get security
fixes without being pushed onto a whole new version. If neither name is on your screen, type
security in the search box at the top of Settings.

Pixel: Settings → System → Software
update. Samsung: Settings → Software
update → Download and install.

In Google’s words, updates roll out gradually and depend on your carrier and device, so it can
take a few weeks to reach your phone. And do not panic if your Galaxy shows an older Android number
than a Pixel — Samsung builds One UI on its own calendar. “Up to date” means newest available
for your phone.

The catch: the “memory cleaner” app is the thing slowing you down

This is why those four fixes did not stick last time.

On Android, cleaner apps cannot do the one thing they advertise. Google closed that door in
Android 14, back in 2023: an app that calls the function for killing background processes can now
only kill its own. Feed it another app’s name and nothing happens. That “1.2 GB freed!” counter is
theater.

Google spells out the damage on the same page: Android keeps apps cached and kills them itself
when it needs memory, and killing them unnecessarily reduces performance and increases
battery drain, because a restart costs far more than resuming a cached app. Then the flat
sentence, in Google’s own documentation — it is not possible for a third-party application to improve
the memory, power, or thermal behavior of an Android device.

To show you that permanent “RAM in use” notification, a cleaner runs a foreground service around
the clock. It is literally the background app that never sleeps — the exact thing it claims to
hunt. Precedent with a name: Clean Master, past a billion downloads, was pulled from the Play Store in
February 2020 — 45 apps from its maker, Cheetah Mobile, went out with it, inside a sweep of nearly
600 apps Google banned for disruptive ads and ad fraud.

On your iPhone, the sandbox stops any app from touching another app’s data, so nothing on the App
Store can clear Instagram’s cache for you. And swiping every app up in the switcher is not
maintenance — Apple says force-quit only when an app is frozen. Craig Federighi, Apple’s software
engineering chief, was asked if he closes apps and if it helps battery life. He answered: “No and no.”

One honest exception: Samsung’s own cleaner at Settings → Battery and
device care → Memory → Clean now is a system app, so it
really does close background apps. Google’s argument still applies, though: the price is a slower
reopen.

Do the storage check tonight, before your phone drops under 20 percent
again — and delete any cleaner app you already installed. We publish
one plain-English guide like this every week — leave your number or email below.