𤯠Wait⦠React 19 is gonna kill useMemo and useCallback?!
A deep dive into React 19 rumors and what it might mean for our beloved (and sometimes overused) memoization hooks. Spoiler: maybe we've been overthinking performance optimization all along.
So I was doomscrolling through DEV comments (as one does when youāre ātaking a short breakā but actually procrastinating for 2 hours š ), and I stumbled on this spicy take:
š āuseMemo
and useCallback
will be useless in React 19!ā
And my brain was like: what?! excuse me, sir, those are literally my security blankets in React.
Me & my love/hate story with useMemo
I remember the first time I learned about useMemo
. It was one of those āyou donāt really need this but hereās a cool trickā things, kinda like discovering console.table
in the browser console (mind = blown).
But also⦠confusing af. Like, do I memoize everything? Nothing? My grocery list? š
// Me, circa 2022, memoizing EVERYTHING
const expensiveCalculation = useMemo(() => {
return 2 + 2; // Very expensive math, clearly
}, []);
const memoizedString = useMemo(() => {
return "hello world"; // Such optimization, wow
}, []);
Then useCallback
came along and I was like, āokay now Iām just wrapping functions for no reason.ā Half the time it fixed nothing, but hey, at least my code looked professional š
Fast-forward a bit ā I got into the habit: oh, function as a prop? slap a useCallback
on it! Expensive calculation? useMemo
it! Woohoo optimization nation!
// My old code be like:
const handleClick = useCallback(() => {
console.log("clicked"); // Very callback, much memo
}, []);
const handleSubmit = useCallback(
(data) => {
submitForm(data); // Definitely needed this wrapper
},
[submitForm]
);
Enter React 19 rumors š
Now, this comment says React 19 is making these hooks basically useless. Like⦠not deprecated, but redundant. The React team is apparently cooking some next-level optimizations, so a lot of manual memoization might just disappear.
Think: React gets smarter ā you get lazier ā code gets cleaner. (yes please š)
I mean, frameworks like SolidJS and Svelte already flex with this whole āfine-grained reactivityā thing, where the UI updates only the stuff that changes. If React adopts something similar, why would I waste brain cells wrapping everything in useMemo
?
What this might look like:
// Current React: Manual optimization everywhere
const MyComponent = ({ items, filter }) => {
const filteredItems = useMemo(() => {
return items.filter((item) => item.category === filter);
}, [items, filter]);
const handleItemClick = useCallback(
(id) => {
onItemClick(id);
},
[onItemClick]
);
return (
<div>
{filteredItems.map((item) => (
<Item key={item.id} onClick={handleItemClick} />
))}
</div>
);
};
// React 19 (maybe?): Just write normal code
const MyComponent = ({ items, filter }) => {
const filteredItems = items.filter((item) => item.category === filter);
const handleItemClick = (id) => {
onItemClick(id);
};
return (
<div>
{filteredItems.map((item) => (
<Item key={item.id} onClick={handleItemClick} />
))}
</div>
);
};
But will it really happen?
Hereās the thing⦠React is like the Marvel Cinematic Universe. Big, messy, tons of fans, lots of backwards compatibility baggage. They canāt just snap their fingers like Thanos and say ālol no more useMemo
ā.
So yeah, maybe in React 19 these hooks wonāt be as necessary, but I doubt theyāll vanish overnight. Theyāll probably still hang around for:
- Old projects that need migration
- Library authors who need fine-grained control
- Paranoid devs (hi, thatās me š)
- Edge cases where manual optimization is still needed
Also, ngl, sometimes memoization is just placebo. Iāve legit wrapped tiny functions in useCallback
thinking Iām saving the world, when in reality Reactās like: ābro⦠that did nothing.ā š
The reality check:
Most of the time, our components arenāt actually slow because of missing memoization. Theyāre slow because of:
- Massive component trees
- Too many re-renders from state changes
- Heavy computations that shouldnāt be in render functions anyway
- Poor data structures
What the experts are saying
The React team has hinted at some wild stuff coming:
- Automatic memoization: React might just figure out what to memoize on its own
- Better scheduling: Smarter about when and how to update components
- Compile-time optimizations: Your build tool might optimize React code before it hits the browser
Dan Abramov tweeted something like āstop premature optimizationā (paraphrasing), and honestly, maybe heās right. Maybe weāve been overthinking this whole time.
My takeaway (aka me pep-talking myself)
Honestly, Iām kinda excited about this future. Because if React 19 really makes useMemo
and useCallback
useless, that means less boilerplate, fewer bugs, and one less thing for beginners (like me!) to overthink.
And thatās a win.
My new strategy:
- Write clean, readable code first
- Profile and measure actual performance issues
- Optimize only when thereās a real problem
- Trust React to get smarter over time
So yeah⦠maybe one day weāll look back and laugh at our old code sprinkled with useMemo
like confetti. Until then, Iāll keep slapping them in my code whenever I panic about performance. Donāt judge me.
// Future me looking at 2024 code:
const needlessOptimization = useMemo(() => {
return "Why did I wrap a string in useMemo? š¤¦āāļø";
}, []);
The bottom line
React 19 might make our manual optimizations obsolete, but thatās actually amazing news. It means we can focus on building great user experiences instead of micro-managing every render cycle.
Plus, if React gets this right, itāll make the framework more approachable for everyone. No more āshould I useMemo this?ā anxiety. No more cargo-cult programming with useCallback.
Just clean, fast React code that works.
Now if youāll excuse me, I need to go remove 47 unnecessary useCallback
s from my current project⦠š
What do you think? Are you excited about potentially simpler React code, or will you miss the control that manual memoization gives you? Let me know in the comments. (when I get time to vibecode a comment section)