Accessing the file system can affect your app's speed and battery life. Reading or writing large files may cause delays and reduce frame rates below 60fps, making the UI feel slow. Frequent file operations can increase memory use and battery drain. Use asynchronous methods to avoid blocking the main UI thread.
Use asynchronous APIs like react-native-fs or expo-file-system to prevent UI freezes. Avoid reading or writing large files on the main thread. Cache frequently accessed data in memory to reduce file reads. Batch file operations when possible. Use background tasks for heavy file processing to keep the UI smooth.
File system access libraries add some size to your app bundle, typically a few megabytes. This is usually small compared to media files your app may handle. Startup time is not directly affected unless you perform file operations during app launch. Delay heavy file reads until after the UI is ready to improve startup speed.
iOS uses a sandboxed file system with specific directories for documents, caches, and temporary files. Android also sandboxes apps but has different directory structures and permissions. Android requires runtime permissions for external storage access on newer versions. iOS apps must declare file usage in their Info.plist for privacy. Always test file paths and permissions on both platforms.
It is likely your app is performing synchronous or heavy file system operations on the main thread during screen load. This blocks the UI and delays rendering. To fix this, move file reads or writes to asynchronous calls or background tasks, and load only essential data initially.