Frontend System Design Essentials: Preload vs. Prefetch

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In this episode of *Frontend System Design Essentials**, we're talking about **preload, prefetch, and lazy loading* — how they work, when to use them, and how they make your frontend apps feel faster and smoother.

You’ll learn the difference between:

`rel="preload"` vs `rel="prefetch"` vs `rel="dns-prefetch"`
Declarative browser hints vs. dynamic JavaScript preloading
How tools like *SWR**, **React Query**, and **Relay* let you preload data in response to user intent
And how *React.lazy()* and *Suspense* help you split and load code on demand

I’ll walk you through a real-world example of a *user profile page* where both the *data* and the *modal component* are preloaded — so when the user clicks, the UI appears instantly.

We’ll also cover best practices:

When preloading helps
When it hurts (like overloading the network with unused assets)
How preload and prefetch complement lazy loading and code splitting

If you're trying to improve perceived performance, reduce spinners, and make your UI feel snappier — this episode is packed with practical tips.

💬 Question for You

Have you used preload or prefetch in your app?

What’s your favorite way to anticipate user interaction and speed things up?

Let me know in the comments ↓

#reactjs #performance #preload #prefetch #systemdesign #systemdesigninterview