Xiaomi Mi 9 slows down: why the smartphone has become slow and how to fix it

Xiaomi Mi 9, released 2019 The year, still remains a popular flagship thanks to the top Snapdragon chipset 855 and 6 GB of RAM, but even these hardware features don't guarantee smooth operation through the computer. 3-4 Owners complain about hanging up when opening applications, long loading of the interface. MIUI, And then suddenly, friezes when you're playing games or shooting videos, and what's the reason? And most importantly, can you get your smartphone back to its normal speed without replacing the components?

In this article, we will discuss 8 Key causes of brakes on the Mi 9, From the trivial (filled memory) to the technical (chip degradation), each item is accompanied by step-by-step instructions for diagnosis and problem solving, taking into account the features of the firmware. MIUI 12/14 And you'll also find a table comparing optimization methods by efficiency and FAQ frequent-question.

1. RAM overload: why the Mi 9 "choked" when multitasking

The Snapdragon 855 chipset paired with 6GB of RAM in 2019 seemed like an unkillable combo, but today it is the minimum threshold for comfortable work. MIUI (Starting from 12th, they consume up to 1.5 to 2 GB of RAM out of the box before they launch user applications. Add in the background activity of messengers, social networks and system processes, and there is critically little free memory.

How does that manifest?

• 🔄 When switching between apps, they are rebooted instead of rebooted (e.g. YouTube or Chrome opens from scratch).
• ⏳ Delays in opening Recent Applications (swipe up with delay on the app) 1-2 seconds).
• 🎮 Lags in games like PUBG Mobile or Genshin Impact, despite high graphics settings.

The solution to the problem depends on its scale:

• 🧹 Background Clearing: Go to Settings → Annexes → Manage applications and manually close unnecessary processes.Automatic cleansing through Security → Optimization often removes the necessary services.
• ⚙️ Disable AutoRun: In the same Application Management menu, select the app → Auto-start → This is especially true for Facebook, TikTok and Chinese services like Mi Video.
• 🔄 Shifting to lightweight firmware: Official global builds MIUI The alternative is Xiaomi.eu firmware (no bloatware) or Pixel Experience (based on pure Android).

⚠️ Warning: If the smartphone still brakes after cleaning the RAM, check the battery status (section 4.

2.Pulled Storage: How 128GB is converted into 5GB free

Xiaomi Mi 9 was released with 64 or 128 GB of memory, but even 128 GB today is critically small for an active user. MIUI It reserves up to 10-15 GB for your needs, and the cache of applications, high-resolution photos (48 MP camera!) and updates quickly eat the rest. When there is less than 10% of free space, the smartphone begins to aggressively slow down — this is due to the work of the file system. F2FS, Optimized for speed, but requires free space.

How do you check?

• 📊 Go to Settings. → If less than 15 percent of the total is free, it's a critical area.
• 🔍 Click Free Space – the system will show what exactly takes up memory (most often it is Cash, Downloads and Media Files).

Ways to make room:

Radical way: reset to factory settings.

Make a backup to Settings → Additional → Backup

Record the username/password from the Mi Account (required to unlock)

Download the latest version of the firmware on PC (in case of failure)

Make sure the battery is charged >50%-->

3.Outdated firmware: why updates MIUI They can both help and hurt.

Xiaomi regularly releases updates for the Mi 9, but not all of them are optimized for aging iron. MIUI 12 on MIUI 14 added new animations and features, but increased the workload on the processor by 15-20:

• 🐢 Slowing down animations when opening/closing applications.
• 🔋 Increased battery consumption (due to background optimization of new services).
• 📱 Self-involved reboots at high load.

How do I check the firmware version?

Go to Settings. → The phone. → Version. MIUI. The latest stable versions for the Mi 9:

• Global: MIUI 14.0.4 (Stable) based on Android 12.
• Xiaomi.eu: 14.0.3.0 (no browser, but requires unlocking the bootloader).

What do I do?

• 🔄 roll back MIUI 12: If the brakes started after the update, you can return to the old version via Fastboot. FAQ.
• ⚡ Install a custom core: For example, FrancoKernel or Kirisakura optimize power consumption and performance.
• 🛠️ Disable unnecessary functions MIUI: 📊 Settings → Display. → Window animation → lay out 0.5x. 🔍 Settings → Confidentiality → Special permits → Auto-start → Disable for all applications except messengers.

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Before rolling back the firmware, check compatibility with your model! Wrong firmware can "brick" your smartphone. Use the Xiaomi Flash Tool and follow the instructions on the forum 4PDA.

4. Battery degradation: how a battery kills performance

Lithium-polymer batteries in smartphones degrade over time, a physical process. In 2-3 years, the battery capacity of the Mi 9 (originally 3300 mAh) can fall to 60-70% of its face value. But few people know that a worn-out battery causes the processor to run in a reduced performance mode (throttling) to reduce power consumption.

• 🎮 Games start to "lay" even on minimal settings.
• 📸 The camera focuses for a long time, and shooting video in 4K interrupt.
• 🔥 The smartphone overheats at the slightest load.

How to check the status of the battery?

1. Install the AccuBattery app (free on Google Play).
2. Charge your smartphone to 100% and wait for the full discharge. The application will show the real capacity.
3. Compare it to the face value: ✅ 80-100% battery normal. ⚠️ 60-80% – Impact on productivity. ❌ Less than 60% – Replacement is required.

Decisions:

• 🔋 Battery replacement: The original battery for the Mi 9 is worth it ~1500–2000 ₽. It is important to choose a service with good reviews – a poor replacement can hurt the fee.
• ⚡ Disabling Battery Optimization for Games: In Settings → Battery → Performance mode select High Performance (but this will reduce your work time).
• 🔄 Battery calibration: 1. Discharge the smartphone before it turns off. 2. Connect charging and wait 100% (don't turn it on!) 3. Turn off charging, turn on the phone and recharge to 100%.

⚠️ Warning: If your smartphone brakes after you change the battery, check the charging connector status. Oxidized contacts can cause false alarms to protect against overheating.

5.Overheating: When the Mi 9 becomes a "hot potato"

The Snapdragon 855 is a powerful but hot chipset. In the Mi 9, it is cooled by a graphite heat pad, which eventually loses its efficiency.°C, triggers thermal throttling, which is a forced processor frequency reduction, which protects against damage, but makes the device slow.

Causes of overheating:

• 🎮 Long-term gaming sessions (especially in Call of Duty Mobile or Genshin Impact).
• 📹 Video recording in 4K@60fps.
• ☀️ Direct sunlight or hot weather.
• 🔋 Fast charging (especially if you use a non-original power supply unit).

How do you diagnose?

• 🌡️ Install. CPU Monitor AIDA64 — They'll show the core temperature of the processor.
• 📊 B Settings → The phone. → System status check the Battery Temperature section.

Cooling methods:

The radical solution is to replace thermopaste, which is offered in service centers for 800-1500 hours. ₽. Effect: Temperature reduction by 10-20°C under load.

6 Viruses and Malware: Myths and Reality

Many users write off the brakes to viruses, but in the case of the Mi 9, it is unlikely. MIUI It has built-in security, which blocks most threats:

• 📱 Advertising software: Some applications (especially from third-party sources) show hidden ads that load the processor.
• 🔍 Mining bots: In rare cases, malicious scripts use smartphone power to mine cryptocurrency.
• 📲 Fake Updates: Fraudsters send links to 'update' MIUI", The ones that actually install spyware.

How do you check?

1. Open Security → Scan and start the check.
2. View the list of installed applications in Settings → Remove suspicious apps (such as System Update or Flash Player).
3. Check the traffic consumption: Settings → SIM-maps and mobile networks → Traffic consumption: Unknown applications with high consumption are a reason to be wary.

If you find a virus,

• 🛡️ Remove it via Security or Malwarebytes.
• 🔄 Reset to factory settings (if the virus is deep in the system).
• 🔒 In the future, install apps only from Google Play and disable installations from unknown sources (Settings) → Confidentiality → Special permits).

⚠️ Note: Some Google Play “optimizers” (e.g. Clean Master or Google Play) DU Speed Boosters are the cause of the brakes. They're constantly running in the background and consuming resources.

7. Hardware problems: when it's not about software

If all the software methods have been tried, but the Mi 9 still slows down, the problem may be in the hardware.

• 💾 Damaged flash memory: There are delays when reading/write data, symptoms are slow opening of the gallery, errors when installing applications.
• 📡 Faulty module Wi-Fi/Bluetooth: Continuous network searches are loading the processor.
• 🔌 Oxidized battery contacts: Lead to false protection alerts and reduced performance.
• 🔧 Chipset dump: The extreme case where the processor physically moves away from the board due to overheating.Requires rations in the service.

How do you diagnose?

• 🛠️ Conduct a memory test with the help of MemTest86 (requires unlocking the loader).
• 📡 Check the stability of Wi-Fi: if the speed drops or the connection breaks, it may be a problem in the module.
• 🔋 Inspect the battery compartment for oxidation (better in the service).

Decisions:

• 💾 Replacement of flash memory: Cost - from 3000 ₽, But not always appropriate for a smartphone in 2019.
• 📡 Supplier of Wi-Fi module: ~2000 ₽, But there is no guarantee of durability.
• 🔄 If you have road repairs, consider selling the Mi 9 for parts and switching to a new model.

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If the smartphone started to brake after falling or getting moisture, there's a 90% chance that it's a hardware problem. Self-diagnosis is powerless here -- you need repairs.

8. Missetting: Little things that kill performance

Sometimes the brakes are not caused by a breakdown, but by suboptimal settings.

• 🎨 Screen resolution: Mi 9 supportive FHD+ (2340×1080), But some users accidentally include HD+ (1560×720), Which leads to blurring and lags when zooming. Check the settings. → Display. → Screen resolution.
• 🔊 Sound Effects: Mi Sound Enhancer in Settings → Sound can cause delays when playing music.
• 📡 Mobile Data Mode: If in Settings → SIM-map → Network type selected Only 4G, Not the car, the smartphone spends extra resources on the search network.
• 🔋 Power saving mode: Ultra mode enabled in Settings → Battery limits performance to 70%.

Optimal settings for speed:

If you have brakes left after all the manipulations, try an alternative launcher. For example, Nova Launcher or Lawnchair work smoother than the standard launcher. MIUI Launcher.

FAQ: Frequent questions about the Xiaomi Mi brakes 9