How to remove lags on Xiaomi Redmi Note 9: from simple settings to deep optimization

Xiaomi Redmi Note 9 remains a popular smartphone even years after its release, but many users face one unpleasant problem: slowing down. Apps open for a long time, animations twitch, and sometimes the device completely freezes for a few seconds. 90% of the time it is not a hardware breakdown, but the result of clogged memory, outdated software or improper settings MIUI.

In this article, we’ll look at all the possible causes of lags, from basic (which even a beginner can fix) to advanced (like manually turning off background processes), how to diagnose a problem, what Redmi Note 9 settings affect performance, and when to think about hardware repair. All methods are tested on current versions of MIUI 12-14 and do not require root rights.

Important: if your smartphone overheats at the slightest load or turns off spontaneously, the problem may lie in a worn-out battery or thermal paste, in which case software optimization will not help - you need a diagnosis in the service center.

1.Diagnosis: Why the Redmi Note 9 is slowing down

Before you start "treatment", you need to understand the source of the problem. Lags on the Redmi Note 9 usually occur for 5 key reasons:

• 📱 Overloaded memory: less than 10% of the available space on the internal drive or cache.
• 🔄 Outdated firmware: MIUI Up to 12th version or irrelevant security patches.
• 🧹 Background processes: autoloading unnecessary apps, duplicate services Google and Xiaomi.
• 🔋 Battery wear: Capacity below 70% of face value leads to trottling (forced performance reduction).
• 🛠️ Hardware malfunctions: damaged flash memory, departed plume or processor defect.

To identify a weak spot, do 3 quick tests:

1. Open Settings → About Phone → Battery status. If the capacity is below 3,500 mAh (originally 5020 mAh), the battery is worn out.
2. Run Settings → Memory → Memory Analysis. If less than 5 GB is free, the system slows down due to space shortage.
3. Install the Throttling Test CPU app from Google Play. If the test shows trottling, the problem is overheating or battery.

If the tests show problems with the hardware (battery, memory, processor), the software optimization will have a temporary effect, in which case you should contact the service immediately. If the problem is software, move to the next section.

2.Memory Cleanup: The First Step to Smooth Work

The most common cause of lag is clogged memory. Redmi Note 9 has 64 or 128 GB of internal drive, but even this is enough to a year or two of use to “clog” the system with unnecessary files.

Start with manual cleaning:

• 🗑️ Remove the app cache: Settings → Annexes → Select an application → Warehouse → Clear the cache.
• 📸 Move photos and videos to Google Photos or external drive. Use the function of Storage optimization in the gallery settings.
• 🎮 Remove unused games and heavy apps (e.g. Facebook, TikTok) that consume resources even in the background.
• 📂 Conduct a deep cleaning through Security → Cleaning (built-in application) MIUI).

For automatic optimization, turn on:

1. Settings → Memory → Autoclean (set a schedule for each week).
2. Settings → Battery → Energy Saving Mode → Optimization (select Balanced Mode).

⚠️ Warning: Do not use third-party cleaners like Clean Master or CCleaner.They often delete important system files and can aggravate lags. MIUI All the necessary tools are already in place.

3. MIUI Optimization: Disabling Unnecessary Functions

MIUI is one of the heaviest Android shells, especially on budget smartphones like the Redmi Note 9. A lot of background processes, animations and duplicate services from Xiaomi/Google eat up resources. By disabling the extra, you can increase FPS animations and speed up the system response.

List of key optimizations:

Another hidden resource eater is Google Play Services, to limit its activity:

1. Go to Settings → Apps → All Apps → Google Play Services.
2. Press Limit Background Activity.
3. Turn off auto-update in Google Play → Settings → Auto-update apps.

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If the interface seems too sharp after disabling animations, set the value 0.75x – this is a compromise between smoothness and speed.

4. Resetting: When nothing helps

If memory cleaning and MIUI optimization fail, the next step is factory reset, a radical but effective method that will bring the smartphone back to its original freshness. On the Redmi Note 9, the reset takes 5-7 minutes and requires no connection to a PC.

How to make a reset without losing data:

1. Create a backup through Settings → Additional → Backup and Reset → Local Backup.
2. Move the copy to Google Drive or an external drive.
3. Perform reset: Settings → Additional → Backup and Reset → Reset settings.
4. After the reboot, restore data from the backup (but don’t restore system settings – only contacts, messages, and media).

⚠️ Warning: Don't use Restore Everything After Reset! This will bring back the old settings that caused the lags. Install the applications manually and adjust the system settings from scratch.

If the smartphone does not turn on after reset or hangs on the Redmi logo, then the firmware has been damaged, in which case you will need to flash through Fastboot (instructions in the next section).

5. Flashing: A last resort for advanced

When neither reset nor cleanup helps, it's left to reinstall the firmware.

• 🐢 The system brakes even after resetting.
• 🔄 Updates MIUI not installed.
• 🚨 Errors like com.android.systemui are stopped.

For Redmi Note 9 (codename merlin) there are 2 official flashing methods:

1. Recovery (saves data, but doesn’t always help with serious crashes): 1. Download the latest stable firmware with [en.miui.com](https://en.miui.com/download.html) (Choose the Redmi Note model 9). 2. Rename the file to update.zip And put it in the root of the memory. 3. Go to Recovery: Turn off the phone, then pinch the power + Loudness up. 4. Choose Install. update.zip and wait for completion.
2. Through Fastboot (full clean installation, requires PC): 1. Install [Mi Flash Tool](https://new.c.mi.com/global/miuidownload/index) on your computer. 2. Download Fastboot firmware for merlin and unpack into a folder. 3. Connect the phone turned off to your PC, holding Volume down + Power (Fastboot mode). 4. In Mi Flash, select the firmware folder and press Refresh → Flash.

After flashing:

• Do not restore a backup copy of system settings.
• Do not install heavy applications for the first 2-3 days (let the system “settle”).
• Update all apps through Google Play.

6. Hardware solutions: when the "iron" is to blame

If the software methods didn't help, the problem lies in the hardware. For the Redmi Note 9, 3 "iron" causes of lag are typical:

1. Worn-out battery: With a capacity below 70%, overheating protection is triggered, and the processor operates at a reduced frequency. ~1500–2500 ₽).
2. Damaged flash memory: If the smartphone “hangs” while reading / writing files, perhaps the eMMC cells fail. You can check through the AIDA64 application (Storehouse → Health status section).
3. CPU overheating: Redmi Note 9 is equipped with MediaTek Helio G85, which is prone to trottling. If the body is heated above 45 ° C, you need to replace the thermal paste (in the service).

How to check the condition of iron:

• 🔋 Battery: Settings → The phone. → Battery status or AccuBattery application.
• 💾 Memory: AIDA64 → Warehouse → Read/write test: If the speed is below 150 MB/s, the memory is degraded.
• 🌡️ Temperature: CPU Monitor (norm to 40)°C in plain, up to 60.°C under load).

⚠️ Warning: If the lagas are left after the battery replacement, check the battery plume.On the Redmi Note 9, it often departs from the board, leading to sudden shutdowns and brakes.

7. Alternative firmware: whether to switch to caste

Some users decide to install custom firmware (such as LineageOS or Pixel Experience) to get rid of the “heavy” MIUI. However, for the Redmi Note 9, this is not always justified:

If you still decide to try caste, follow the instructions:

1. Unlock the bootloader via [Mi Unlock Tool](https://en.miui.com/unlock/) (requires a Mi Account binding and a wait of 7 days).
2. Install TWRP Recovery for merlin (instructions at [XDA Developers](https://forum.xda-developers.com/)).
3. Download the appropriate firmware (e.g. [Pixel Experience](https://download.pixelexperience.org/)) and install it via TWRP.

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Custom firmware is only suitable for advanced users. For most owners of the Redmi Note 9, the best option is a pure MIUI with redundant functions disabled.

FAQ: Frequent questions about lags on Redmi Note 9