🚀 Boosting React Native Performance with Caching — Made Simple

#reactnative #caching #database #applicationperformance

In this guide, we’ll break down what caching is, why it matters in React Native, and how to implement it with some handy tools and libraries.

🔍 Why Should You Care About Caching?

Mobile apps run on devices that have limited memory and storage — and let’s be honest, internet connections aren’t always reliable. Caching helps your app:

Load faster by avoiding repeated API calls
Work offline or in poor network conditions
Feel smoother by loading images and data locally

🧰 Types of Caching in React Native

Not all caching is created equal. Let’s look at the most useful types:

1. In-Memory Caching

This is the quickest way to cache data, storing it temporarily in the app’s memory.

Great for UI state or short-lived data
Libraries like Redux, Zustand, or React’s Context API can handle this
But remember: once the app closes, this data is gone

2. Persistent Caching

This is for data that should stick around, even after restarting the app.

Useful for login tokens, user settings, or cached API responses
Use tools like AsyncStorage or the faster, more secure MMKV
Keeps your app functional even without an internet connection

3. Image Caching

React Native doesn’t cache images well by default, which can cause slow load times and unnecessary data use.

Use react-native-fast-image for proper image caching and better performance
Especially useful for apps with lots of images (e.g. shopping, social media)

4. API Response Caching

Instead of hitting the server every time, cache API responses locally.

Helps reduce load on your backend
Makes screens load quicker
Tools like MMKV, React Query, or SWR can help manage this
Built-in support for stale data and revalidation

🔐 MMKV for Fast Persistent Caching

MMKV is a high-performance storage solution that’s great for caching data on the device.

📦 Install MMKV

npm install react-native-mmkv

⚙️ Setup MMKV

// storage.ts
import { MMKV } from 'react-native-mmkv'

export const storage = new MMKV()

export const setCache = (key: string, value: any) => {
  storage.set(key, JSON.stringify(value))
}

export const getCache = (key: string) => {
  const json = storage.getString(key)
  return json ? JSON.parse(json) : null
}

🔁 Caching API Responses

Let’s create a simple hook to fetch data and cache it using MMKV.

// useCachedFetch.ts
import { useEffect, useState } from 'react'
import axios from 'axios'
import { getCache, setCache } from './storage'

export const useCachedFetch = (url: string, cacheKey: string) => {
  const [data, setData] = useState<any>(null)
  const [loading, setLoading] = useState(true)
  useEffect(() => {
    const fetchData = async () => {
      const cached = getCache(cacheKey)
      if (cached) {
        setData(cached)
        setLoading(false)
        return
      }
      try {
        const response = await axios.get(url)
        setData(response.data)
        setCache(cacheKey, response.data)
      } catch (e) {
        console.error(e)
      } finally {
        setLoading(false)
      }
    }
    fetchData()
  }, [url])
  return { data, loading }
}

🧪 Usage

const { data, loading } = useCachedFetch('https://api.example.com/products', 'products')

if (loading) return <ActivityIndicator />
return (
  <FlatList
    data={data}
    renderItem={({ item }) => <Text>{item.name}</Text>}
  />
)

🖼️ Image Caching with react-native-fast-image

For static images or images fetched over the network, use react-native-fast-image to enable caching and performance boosts.

npm install react-native-fast-image

import FastImage from 'react-native-fast-image'

<FastImage
  style={{ width: 100, height: 100 }}
  source={{
    uri: 'https://example.com/image.jpg',
    priority: FastImage.priority.normal,
    cache: FastImage.cacheControl.immutable,
  }}
/>

⚠️ Gotchas & Best Practices

Set a TTL (Time To Live) if the data can go stale
Don’t store sensitive info unless it’s encrypted
Clear cache when the user logs out or when data becomes irrelevant

📌 Conclusion

Caching is a simple but powerful way to make your React Native app feel lightning fast and reliable. With tools like MMKV and FastImage, you can easily implement smart caching strategies that keep users happy — even when their internet isn’t.

Happy Caching! 💙