Xiaomi Redmi Note 9 slows down: reasons and 10 proven ways to speed up the smartphone

Why Redmi Note 9 is Slow and How to Fix It

Your Xiaomi Redmi Note 9 suddenly started to slow down, apps are opening for a long time, and animation is twitching? This is a common problem even for relatively powerful smartphones with a MediaTek Helio G85 processor and 4 GB of RAM, the reasons can be due to software failures and physical wear of components – especially if the phone is used for 2-3 years.

In this article, we will look at all possible causes of brakes, from overloaded memory to battery degradation, and give step-by-step instructions for eliminating lags. Importantly, some methods (for example, resetting to factory settings) will lead to data loss, so make a backup copy in advance.

If the phone doesn't just brake, it turns off when it's loaded or overheated, the problem could be the processor's thermal paste or the battery malfunction, which requires repairs at the service center, and the rest of the problems are often solved on their own.

1. Clearing cache and unnecessary files

The most common cause of brakes is clogged memory. System cache, residual files of deleted applications and debris from messengers (such as Telegram or WhatsApp) take up space and slow down. Start with a simple cleanup:

• 🧹 Cleaning the application cache: go to Settings → Annexes → App management, select any app (like YouTube or Facebook) and click Clear Cache. Repeat for all commonly used programs.
• 🗑️ Garbage Removal: Use the built-in Security app (shield icon) → «Cleanup» → «Deep cleaning. It will find unnecessary files, duplicate photos and large files.
• 📁 Manual Memory Check: Open Files (the “Category” tab) and delete: Downloaded APK-files (Download folder); Old backups (MIUI/Backup); Cash cart (Android/data — game-file).

If less than 10% of the memory is available, the system starts to slow down due to lack of space for temporary files. Optimally leave 15-20 GB free of 64/128 GB.

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After clearing the cache, some apps (like Google Maps or Instagram) will take longer to load when you first run – that’s fine.

2. Disconnect background processes and autoboots

MIUI is known for aggressively optimizing background processes, but sometimes it works against the user: messengers don't get notifications and games are reloaded. On the other hand, too many apps in the background are the direct cause of lags. Find a balance:

• ⚙️ Background activity restriction: Go to Settings → Battery and productivity → Battery management. Select App Selection and tick the program that should not work in the background (such as rarely used games or social networks). For critical applications (such as Telegram), select No Limits mode».

Shutting down autoboot

1. In the same menu (Battery Management) tap on "Sunset".
2. Turn off autoboot for unnecessary apps (e.g. AliExpress, Wildberries, games).

After these actions, the phone will wake up less often to update background tasks, which will save the CPU and RAM resources.

3. Update firmware and reset settings

Outdated firmware is one of the main reasons for the brakes. Xiaomi regularly releases updates that correct errors and optimize the work of MediaTek Helio G85.

1. Go to Settings → About the phone → System update.
2. Click on "Check Updates." If a new version is available, download and install.
3. After the update, be sure to restart the phone.

If the update didn't work, try resetting to factory settings. This is a radical method, but it removes all settings and debris accumulated over time:

⚠️ Warning: Reset will delete all data, including photos, contacts and messages. pre-backup through Settings → Additionally. → Backup and Reset or Mi Cloud.

• 🔄 Soft reset (saves files in memory but resets settings): Go to Settings → Additionally. → Backup and reset → Settings reset. Select Reset (not to be confused with Reset all settings»!).

Hard discharge

1. Turn off the phone.
2. Press Volume Up + Power before the Mi logo appears.
3. From the Recovery menu, select Wipe Data → Wipe All Data.
4. Confirm the action and wait for the reboot.

Backup contacts |Save photos to PC/cloud |Write down account passwords |Make sure your phone is 50%+ charged

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4. Checking the battery and overheating

Over time, the Redmi Note 9’s 5,020 mAh battery degrades, and its actual capacity decreases, so if the phone runs out in a few hours or shuts down at 20 to 30 percent, it directly affects performance: the system begins to limit the power of the processor to save power.

How to check the status of the battery:

1. Enter the dialer code ##4636##.
2. Select Battery Information. See Health: Good is normal; Unknown or Dead is required to be replaced.

Also note the overheating. If the phone gets warmer than 45°C (you can check it through the AIDA64 app), the Helio G85 processor starts trottling (reduced frequency), which leads to brakes.

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If the battery is swelling (the body of the phone is deformed) - immediately turn off the phone and contact the service.

5. Optimization of animation and MIUI interface

MIUI is known for its heavy animations, which can slow down on the Redmi Note 9, especially after updates.

• ⚡ Disable animation: Activate Developer Mode (as in spoiler above). Go to Settings → Additionally. → For developers. Find items: The scale of the window animation → Select No Animation; Scope of Transition Animation → No animation; duration of animator → Off..
• 🎨 Simplifying the interface: C Settings → Screen. → Select “Simple Mode” (reduce the load on the screen) GPU). Turn off the live wallpaper: Settings → Wallpaper. → Static wallpaper.

These changes will make the interface less smooth, but will significantly speed up the opening of applications and reduce scroll delays.

6.Verification for viruses and malware

Viruses and ad units often cause brakes, which can disguise themselves as system processes (e.g. com.android.system) and load the processor.

1. Install an antivirus (such as Malwarebytes or Dr.Web Light) and perform a full scan.
2. Check the list of installed applications: Go to Settings → Apps → Application Management. Sort by installation date and remove suspicious programs (especially with names like Super Cleaner, Battery Saver Pro).
3. Disable Administrator Rights for Unknown Applications: Settings → Passwords & Security → Application Permissions → Device Administrators.

⚠️ Attention: Some Google Play "optimizers" are causing the brakes themselves. Use only official tools MIUI (security).

7. Thermopaste replacement and repair (if nothing worked)

If all software methods have been tried, but the Redmi Note 9 is still braking and overheating, the problem may be physical wear and tear.

• 🔥 Dried thermopaste: Over time, the thermal interface between the processor and the radiator loses properties, leading to overheating and trottling. ~1000–1500 ₽).
• 🔋 Worn-out battery: If the capacity falls below 70% of the original, the phone will lose performance dramatically. It will cost 1500-2500 to replace the battery ₽ (Xiaomi).
• 🛠️ Damaged motherboard: In rare cases, brakes are caused by microcracks or contact oxidation.

It is not recommended to disassemble the Redmi Note 9 yourself - there is a high risk of damaging the plumes or display.

FAQ: Frequent questions about the Redmi Note 9 brakes