MMKV is a key-value storage library optimized for speed and low latency. It uses memory-mapped files to read and write data quickly, which helps your app maintain smooth 60fps animations and fast UI responses. Because it avoids heavy disk I/O on the main thread, it reduces jank and battery drain compared to traditional storage methods like AsyncStorage.
To keep your app running smoothly, use MMKV asynchronously and avoid blocking the UI thread. Batch writes when possible and avoid frequent small writes. Use MMKV's native methods directly instead of wrapping them in extra JavaScript layers. Also, clear unused keys to keep the storage lean and fast.
Integrating MMKV adds a small native library to your app, typically increasing the bundle size by a few megabytes. This is a moderate increase but justified by the performance gains. Startup time impact is minimal because MMKV initializes quickly. Lazy loading MMKV instances can further reduce startup delays.
MMKV is supported on both iOS and Android with native implementations. On iOS, it uses NSFileHandle and memory mapping with mmap. On Android, it uses JNI to access native C++ code. Both platforms benefit from fast reads and writes, but Android requires proper ProGuard rules to avoid stripping MMKV classes. Also, Android apps must handle multi-process access carefully.
Using MMKV complies with both Apple App Store and Google Play policies as it stores data locally without transmitting sensitive user data. Ensure you do not store sensitive information unencrypted. For sensitive data, use MMKV's encryption features. Also, respect user privacy and provide clear disclosure if you collect or store personal data.
If your screen loads slowly despite using MMKV, you might be doing heavy synchronous reads or writes on the main thread. Another cause could be loading large amounts of data at once instead of lazy loading. Check if you are initializing MMKV multiple times or not reusing instances. Optimizing these will improve load time.