Xiaomi Redmi Note 9 slows down and lags – what to do in 2026?

Xiaomi Redmi Note 9

slowdown

Redmi Note 9

Pro/Pro Max

In this article, we will look at all possible causes of brakes, from overloaded memory to outdated firmware, and give step-by-step instructions for restoring performance. Particular attention will be paid to the specific “diseases” of the Redmi Note 9 associated with its hardware platform (MediaTek Helio G85) and MIUI. All solutions are tested on current versions of the software (including MIUI 14 and Android 12).

If you are not sure of your technical skills, start with the simplest ways (cleaning the cache, turning off animations) and then move on to radical measures (resetting settings or flashing).

1. Causes of brakes Redmi Note 9: hardware vs. software

Before you start "treatment", you need to understand what causes the hanging, and all the causes are divided into two large groups:

Hardware problems (resolved by repair or replacement of components):

• 🔋 Battery wear – when the battery is degraded to 70% of capacity, the smartphone begins to artificially limit performance to extend the life of the battery.
• 🔥 Overheating of the processor - MediaTek Helio G85 Prone to trottling (automatic frequency reduction) when heated above 60°C.
• 💾 Flash memory problems – the cheap 5.1 eMMC in the Redmi Note 9 wears out over time, especially if data is often recorded/deleted.
• 📱 Mechanical damage – falls or moisture can damage contacts on the motherboard.

Software problems (solved by settings or flashing):

• 🗑️ Cluttered memory – less than 10% of the free space on the internal drive leads to lags.
• 🤖 Outdated firmware — MIUI 12.5+ often conflicts with new applications.
• 🧹 Cache and junk files – temporary application data can take up gigabytes of memory.
• 🚫 Background processes – some applications (especially Chinese) run hidden services that load CPU.

And software causes are usually 80 percent of the time, and you start diagnosing them, and it's faster and cheaper.

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To check the battery status, type ##4636## in the dialer, then select "Battery Information." If the health score is below 80%, it's time to change the battery.

2. Cleaning up memory and cache: the first step to speeding up

If the Redmi Note 9 started to slow down suddenly, it is likely that overloaded memory is to blame. Even with free space, the system can run slowly due to fragmented data or cache.

How to make the right place:

1. Remove unnecessary apps through Settings → Apps → App management. Pay attention to games and social media – they take up the most space.
2. Move photos and videos to the cloud (Google Photos, Mi Cloud) or to a memory card.
3. Clear the cache of system applications: go to Settings → Memory → Clean up and click “Clean up garbage”.
4. Turn off the automatic saving of media files from messengers (WhatsApp, Telegram).

For deep cleaning, use the built-in MIUI Optimizer tool:

1. Open Security. → Cleanup.
2. Press "Deep Clean" and wait for the analysis to be completed.
3. Delete all temporary files and application residues found.

The critical threshold of free memory for Redmi Note 9 is 3 GB. If less, the system begins to actively use the swap file on the drive, which slows down 5-7 times.

Remove unused applications|Transfer your video/photo to the cloud|Clear the cache through MIUI Optimizer|Disable autosave in messengers|Check the vacant space (should be available) ≥3GB)-->

3. MIUI Optimization: Disabling Unnecessary Functions

MIUI is known for its abundance of background processes and "hidden" functions that consume resources, many of which can be safely turned off without compromising stability.

What can be turned off to accelerate:

• 📡 Auto-update MIUI: Go to Settings. → The phone. → Update the system and disable automatic check.
• 🔍 Search for Xiaomi applications: in Settings → Additionally. → Search to disable "Show results from the Internet".
• 📊 Analytics and reports: in Settings → Memory. → Autorun disable "Send error reports".
• 🎵 Mi-Pei: if you do not use wireless headphones Xiaomi, disable the service in Settings → Connected devices → Mi Pay.

Another effective way is to turn off the animation of the interface, which won't speed up the processor itself, but visually, the system will appear faster.

1. Activate Developer Mode (7 times click on "Version" MIUI" In Settings → The phone).
2. Back to Settings → Additionally. → For developers.
3. Find the items "Scale of window animation", "Scale of transition animation" and "Duration of animation" - set the value to Disable or Animation disabled.

If the device is still slowing down after this manipulation, try rolling back MIUI updates to a more stable version, for example, many users note that MIUI 12.0.8 runs smoother than MIUI 12.5+ on the Redmi Note 9.

4. Resetting settings: a radical solution

If none of the previous methods worked, it's time for a hard reset that will delete all data from the device, so back up first:

• 📱 Save your contacts in a Google account or on SIM-map.
• 🖼️ Transfer the photo/video to a PC or memory card.
• 🔑 Write down passwords from Wi-Fi and accounts (they will reset!).

How to make a reset through the menu:

1. Open Settings → About Phone → Backup and Reset.
2. Select "Settings Reset."
3. Check the box "Clear internal memory" (optional if you want to delete all files).
4. Confirm the action and wait for the reboot (it will take 5-10 minutes).

If the smartphone freezes and does not respond to touch, reset through Recovery mode:

1. Turn off the device.
2. Press the Power button + Volume up until the Mi logo appears.
3. In the Recovery menu, select Wipe Data → Wipe All Data (manage volume buttons, confirmation – power button).
4. After reset, select Reboot.

⚠️ Note: Some firmware may require re-activation of the device via Mi-account after reset. If you forget your username/password, it will be difficult to unlock your phone - link your account in advance!

5. Firmware Update: When It Helps (and When It Doesn't)

The performance of the Redmi Note 9 is heavily influenced by the MIUI version. Xiaomi regularly releases patches that fix the lags, but sometimes new updates, on the contrary, make things worse.

How to upgrade MIUI without risk:

1. Connect to stable Wi-Fi.
2. Charge the battery at least 50%.
3. Go to Settings → About the phone → System update.
4. If the update does not come automatically, download it manually from the official website and install it through "Select a firmware file".

If the smartphone has become more braking after the update, go back to the previous version (instructions in the spoiler above). On the Redmi Note 9 with 4 GB of RAM, MIUI 13.0.4 is considered optimal - it offers a balance between new features and performance.

6.Iron problems: when it's time to get into service

If all software methods have been tried and the Redmi Note 9 is still slowing down, the problem lies in the hardware.

• 🔥 The smartphone overheats even with simple tasks (for example, in messengers) - the wear of the thermal paste or damage to the processor is possible.
• 🔋 The battery is discharged in 2-3 hours with minimal load - battery degradation to 60% and below.
• 💥 Apps fly out with an error or the phone spontaneously reboots - problems with RAM or flash drive.
• 📉 In benchmark tests (e.g. AnTuTu) scores below 150,000 are critical performance drops.

Cost of repair (estimated prices in 2026):

• Battery replacement: 1,500–2,500 ₽ (original / 800-1 200 ₽ (analogue).
• Thermopaste replacement: 500–1000 ₽.
• Flush memory soldering: 3000–5,000 ₽.
• Replacement of motherboard: 6,000–10,000 ₽ (Unprofitable for a budget smartphone).

Before visiting the service, check the warranty status:

1. Go to the Xiaomi Warranty Check website.
2. Enter your device’s IMEI (you can find it by command *#06#).
3. If the warranty is in place, repairs can be free (for example, when the battery is bloated).

⚠️ Note: If you have previously unlocked the bootloader or installed custom firmware, the warranty is canceled. In this case, the official Xiaomi service will refuse free repairs.

7. Alternative firmware: should you switch to caste?

Some users decide to install custom firmware (such as LineageOS, Pixel Experience or Havoc-OS) to get rid of MIUI brakes. This can give an increase in performance, but has serious disadvantages:

The advantages of custom firmware:

• ⚡ More smooth work due to the lack of “extra” services Xiaomi.
• 🆕 Up-to-date versions of Android (for example, Android 13 instead of Android 10 in stock) MIUI).
• 🔧 Flexible interface and performance settings.

Cons and risks:

• 🚫 Loss of warranty (requires unlocking the bootloader).
• 📱 Possible bugs with camera, sensors or mobile communications.
• 🔋 Faster battery discharge (not all firmware is optimized for Helio) G85).
• 🛠️ Difficulty of installation for beginners (risk of "bricking" the phone).

If you do, follow this instruction:

1. Unlock the bootloader through the Mi Unlock Tool (requires a tied Mi Account and wait 7 days).
2. Install TWRP Recovery for Redmi Note 9 (you can download it on the official website).
3. Download the right firmware (e.g. Pixel Experience for merlin is codenamed Redmi Note 9).
4. Sweat through TWRP, pre-made backup!

For beginners, we recommend starting with the firmware Xiaomi.EU - this is a modified MIUI without Chinese software, but with the preservation of all the functions of the camera and sensors.

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Custom firmware gives you performance gains, but it's not warranty-free and can cause iron problems. Beginners should limit themselves to optimizing stock MIUI.

FAQ: Frequent questions about the Redmi Note 9 brakes