What are the practical performance considerations of reading from SharedPreferences repeatedly throughout your app, and how does properly caching those particular values in memory help meaningfully avoid genuinely unnecessary repeated disk access?

While a single individual SharedPreferences read operation is generally quite genuinely fast, repeatedly reading that exact same particular value many separate times throughout your app, such as checking a specific user preference on essentially every single individual widget rebuild, can still genuinely add up to meaningfully unnecessary overhead over time, and a genuinely common recommended optimization pattern involves properly loading all of your app's own relevant preferences once during startup, caching those particular values in memory using a dedicated settings or preferences service class, and then having the rest of your app genuinely read from that in memory cache instead, only actually writing back to SharedPreferences itself whenever a given specific value genuinely actually changes.

class SettingsService {
  bool _darkMode = false;
  bool get darkMode => _darkMode;

  Future<void> loadSettings() async {
    final prefs = await SharedPreferences.getInstance();
    _darkMode = prefs.getBool('darkMode') ?? false;
  }
}