How to speed up the Xiaomi Redmi Note 9: from cleaning cache to hidden MIUI settings

Xiaomi Redmi Note 9

MediaTek Helio G85

MIUI

This article covers practical acceleration methods, from basic (cache cleaning) to advanced (system processes shutdown). All methods are tested on the Redmi Note 9 with MIUI 12-14 and do not require root rights. Importantly, the efficiency depends on the current condition of the phone. If the smartphone “choked” even after optimization, it may be time to think about replacing the battery or flashing.

Before you start settings, check the CPU and memory boot.

1. Open Settings → About the phone → System status.
2. Click 5 times on the "MIUI version" item - the developer menu will open.
3. Return to Settings → Additional → For developers and turn on “Debugging by USB” and “Show CPU boot”.

If you have a 70 percent or more on the top right of the screen, the system is overloaded. We're going to optimize.

1.Cache and garbage cleanup: the first step to speed

App cache and system debris are the main “brakes” of the Redmi Note 9. Even after deleting programs, their temporary files remain in memory, taking up 3-5 GB of space. Cleaning the cache will not delete your data (photos, messages, accounts), but will free up resources for the system to work.

How to clean the cache manually:

• 📱 Go to Settings. → Annexes → Application management.
• 🔍 Select an app (start with the frequently used ones: Chrome, Facebook, Instagram).
• 🧹 Click on Clear Cache (not to be confused with Clear Data – this will delete logins!).
• 🔄 Repeat for all applications with a cache size > 100MB.

For automatic cleaning, use the built-in Security app:

1. Open Security. → Cleanup.
2. Click on “Deep Clean” and wait for analysis.
3. Delete unnecessary files (especially pay attention to “App Remains” and “Big Files”).

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If, after cleaning the cache, the applications load longer on the first run, that's OK, and the cache is recreated to speed up the rest of the work.

For advanced users, the hidden MIUI Cleanup function removes system debris that is not available through standard settings to activate it:

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From the menu that opens, select Usage Statistics → Clean MIUI. This method removes up to 1-2 GB of hidden logs and temporary files, but can reset some system settings.

2. Optimization of RAM: what to turn off so that it does not slow down

Redmi Note 9 with 4 GB of RAM often suffers from memory shortages due to background MIUI processes. The system aggressively caches applications, but does not always correctly manage resources.

First, check which apps consume the most memory:

• 📊 Go to Settings → About Phone → System Status → Memory Use.
• 🔍 Note applications marked "Background Process" - they can be limited.

How to reduce the load on RAM:

• 🚫 Turn off autorun: Settings → Applications → Application management → Autorun. Turn off autorun for all applications except instant messengers and system services.
• 🔄 Limit background activity: In the same app settings, select “Limit background activity” for Facebook, TikTok, games.
• ⚡ Turn on Performance Mode: Settings → Battery → Performance Mode. This will turn off background synchronization and speed up work, but reduce battery life.

For power users: disable MIUI animations, which slows down switching between tasks. Activate Settings → Additional → For developers and install:

• The scale of window animation → Disable animation
• Scope of animation transition → Disable animation
• Animator Time → 0.5x

3. firmware update: why the old MIUI is slowing down

The Redmi Note 9 slowdown is often due to the outdated version of MIUI. Xiaomi regularly optimizes firmware for older models, closing the "holes" in performance. For example, MIUI 14 for the Redmi Note 9 added:

• 🔧 Optimize memory consumption by 10-15%.
• ⚡ Accelerated application loading thanks to a new caching algorithm.
• 🛡️ Corrections to prevent fragmentation of internal memory.

How to update the firmware without losing data:

1. Connect to Wi-Fi (update "over the air" weighs 1.5-2.5 GB).
2. Go to Settings → About the phone → System update.
3. Click “Check Updates” and wait for the download.
4. Close all applications before installing and charge your phone at least 50%.

If the update does not come automatically, check the firmware region:

• 🌍 Settings → Additional → Region should match your country (e.g., “Russia” for Russia).
• ⚠️ Do not install firmware for other regions, as this may cause problems with the mobile network and NFC.

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Updating through Recovery (manual) gives more control, but requires downloading the full firmware package (2-3 GB) and can reset settings.

Compatibility table for Redmi Note 9 (model merlin):

⚠️ Warning: If your phone is slower after the upgrade, reset the cache via Recovery. Turn off the device, press Power + Volume up, select Wipe Cache Partition.

4. Disabling unnecessary system applications and services

MIUI default installs dozens of system applications that run in the background and consume resources, some of which can be turned off without root permissions without being completely deleted, which will free up to 500-800 MB of RAM.

List of safe applications to disable (do not affect system stability):

• 🎵 Mi Music is a standard player (if you use Spotify or Yandex Music).
• 📺 Mi Video - Video player (replace with VLC or MX Player).
• 📰 Mi Browser is an ad browser (install Chrome or Firefox).
• 🛒 GetApps - a branded app store (duplicates Google Play).
• 📡 Mi Roaming – roaming service (needed only abroad).

How to turn it off:

1. Go to Settings → Applications → Application Management.
2. Select the app from the list above.
3. Click "Disable" (not "Delete"!).
4. Confirm the action – the application will disappear from the menu and stop working in the background.

For advanced: some system services can be disabled via ADB (no root), for example, to remove ads in MIUI:

adb shell pm uninstall --user 0 com.miui.analytics


adb shell pm uninstall --user 0 com.xiaomi.midrop

The full list of commands for Redmi Note 9:

⚠️ Warning: Disabling system applications via ADB may cause the camera or mobile network to run unstable. Before experimenting, check for interoperability on the 4PDA or XDA-Developers forums.

5. Transfer applications to memory card: unloading internal memory

Fragmentation of internal memory is one of the main reasons for the Redmi Note 9 brakes. When less than 10% of the available space is left, the system begins to “choose”, the solution is to transfer some applications to the microSD (if installed).

How to move applications:

1. Insert a memory card (UHS-I U3 or higher is recommended).
2. Go to Settings → Applications → Application Management.
3. Select an app (such as WhatsApp or Telegram).
4. Click on “Storage” → “Change” → select a memory card.

Limitations of the method:

• ❌ Not all applications support portability (especially games and system utilities).
• ❌ Once ported, the application may run slower (depending on card speed).
• ❌ Application updates will be installed on internal memory.

Alternatively, use the memory card as an internal storage (formatted as part of the system):

1. Go to Settings → Storage → Memory Map.
2. Click on “Format as internal” (all data on the map will be deleted!).
3. After formatting, the system will suggest transferring the application data.

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If the application starts to crash after transferring to SD, return it to internal memory. Some programs (for example, banking) block work from external media.

6.Reset to factory settings: a last resort

If all previous methods failed, it would be a hard reset, which would delete all the data, but it would return the phone to factory speed, and on the Redmi Note 9, it would take 5-10 minutes to reset and solve 90 percent of the performance problems.

How to make a reset without losing important data:

1. Backup: 📱 Contacts: export to Settings → Contacts → Import/Export. 📷 Photo/video: copy to PC or cloud (Google Photo, Yandex Drive). 🔑 Passwords: enable sync in Google Account.

Settings → About the phone → Resetting settings

Select Reset All Settings (not to be confused with Network Settings Reset!).

Confirm the action and wait for the reboot.

After discharge:

• ⚡ Do not restore data from a backup right away – check the speed of a clean system first.
• 🔄 Install only the necessary applications (avoid cluttering»).
• 🛡️ Turn off auto-update apps on Google Play.

⚠️ Warning: If the phone still brakes after reset, the problem may be in the hardware (a worn-out battery, damaged flash memory), in which case only replacement components will help.

7.Alternative firmware: when MIUI is no longer salvageable

If MIUI optimization is not working, consider flashing it on custom firmware. Redmi Note 9 is popular:

• 🔧 LineageOS is a pure Android without the unnecessary services of Xiaomi.
• ⚡ Pixel Experience – firmware with Google Pixel interface and optimizations for weak devices.
• 🛡️ Havoc-OS is a customizable firmware with improved memory management.

Advantages of custom firmware:

• 🚀 Work acceleration of 30-50% by removing the heavy shell MIUI.
• 🔋 Improved Autonomous Time (up to +20% over time)
• 🔒 No advertising and no system "spies."

Risks and requirements:

• ⚠️ An unlocked bootloader is required (the procedure will reset all data!).
• ⚠️ There may be bugs with a camera or mobile network (depending on the firmware version).
• ⚠️ Xiaomi’s warranty will be cancelled.

Installation instructions (briefly):

1. Unlock the bootloader through the official Xiaomi tool.
2. Install TWRP Recovery (Castom Recovery for Firmware).
3. Download firmware (like LineageOS) and GApps (Google services).
4. Flow through TWRP (order: firmware → GApps → Magisk for root rights).

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Custom firmware requires technical skills, and if you've never flashed your phone, start with the official MIUI version or consult a specialist.

FAQ: Frequent questions about the Redmi Note 9 acceleration