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Don't Optimize Your React App, Use Preact Instead

Preact - Performance Optimization by default

A few months ago, I wrote an article based on optimizing react loading time, and most of the reader's comments were to try Preact to get default optimization. So I decided to try preact with the same app used for the previous article. Let's first get an intro about Preact.

Preact is a React alternative library with all the react features!.. Preact is a 3KB library. It is very small compared to react, as react and react-dom gzip size is around 41KB excluding react-scripts based on bundlephobia. Some highlighted features of preact are

  1. Lightweight Virtual Dom
  2. Small in Size
  3. Performance optimized by default
  4. Integration is simple
  5. PWA by default

Now let's see preact in action.

I have developed the same app in React and Preact to test the app performance.





For react app I used Create React App and for Preact used preact-cli. Preact also gives an option to convert your existing react app to preact using preact-compat, but I have built an app from scratch to see the best result.

To compare both app performances, I used GTmetrix and hosted both apps in Netlify.

React App Performance

Below is the score given by GTMetrics for React-based App. I have used Route Based Code Splitting for the dashboard Component. The performance is 80% with B grade, largest content paint (LCP) and Layout Shifting (CLS) seems low.


As we see in the below image, the entire page is loaded in 2 sec, First Content Paint is around 1 sec. Seems the performance is Not bad.


ReactJS Loding Frames

Preact App Performance

All the metrics are in Green!!!. Seems the same app in Preact scored 100% with an A grade in GTMetrix. The largest content paint (LCP) is less than 500ms, No Layout Shifting (CLS) happened.


This looks very impressive. Preact optimized our dashboard app quite well. The performance is drastically increased compared to React. Let us check the Loading time


PREACT Loding Frames

As we see in the above image. The entire App loads in 1.3 secs and the Time to First Byte (TTFB)is 179ms !!. Preact seems very faster compared to React and it handles everything by default.





As looking at the page loading side by side, Preact app loads well ahead compared to React and The Time to interact is also faster than react app. Preact is Progressive Web App(PWA) by default so instant loading on repeat visits.


Preact also gives some useful warning reg bundle size increase during the build as below


Suspense and Lazy

Some limitation I faced when converting to Preact is that Suspense and lazy loading are experimental and don't support on production as of now. but route based code splitting is enabled by default for the routes directory.


  1. Preact
  2. Difference to React


As based on the above comparison Preact leads in all parts. Due to reduced library size and fast, Preact allow us to focus on developing features instead of manual optimization.

Thank you for reading.

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Top comments (18)

nssimeonov profile image

Then you realize - a lot of components you had don't work with preact, because they were made for react. Then you realize, that you have to implement a lot of functionality that comes out of the box with react... and suddenly you realize why react has a bigger footprint.

And the less code YOU write, the less bugs you have to fix, because let's agree on that - the bigger the codebase the more bugs there are.

Just my .02c

brianmcbride profile image
Brian McBride

Imagine if there were a standard for components that could work across all the various front-end libs and frameworks.

Oh, there is?
Of course, React doesn't support them properly.

While I do appreciate what React has given to the community as a whole - it would be so much better if we could get to a point where people are developing web components and then we can just focus on the other libs we need.

Just my .01c (yeah, it's a bargin today)

nssimeonov profile image

Yes, if you start a new project you can pick anything. And I wouldn't pick neither React nor Preact - I like Vue better.

But if you are handed a react codebase, converting it to preact isn't a one-day task and the bigger the project the more problems you will meet.

I'm working on the opposite conversion: Preact->React, and our company chose to do so for a reason.

leob profile image

Couldn't have said it better ... look before you leap, things aren't always what they seem, there are always tradeoffs, and in most cases "it depends".

wintercounter profile image
Victor Vincent

Once we changed experimentally ~2 years ago the codebase to preact and we had decreased pageload times reported both by devtools and analytical tools, even tho evaluation times improved. We reverted. Possibly this improved since then.

However, as it was pointed out, Suspense and Lazy are experimental, React 18 is around the corner with even more features. It simply means preact will be one step behind, no matter what. Not saying it's anyone's fault, everyone can decide on their own which one is more benefitial/important for their project.

leob profile image
leob • Edited

There's no such thing as a free lunch ... there are always trade-offs ... performance gains might be marginal and unnoticeable in real world usage ... if it sounds too good to be true, it probably isn't true.

rschristian profile image
Ryan Christian

preact-compat is the legacy compat, and isn't used in modern apps. Compat lives in core since v10 (which has been out for 2+ years), see v10/upgrade-guide

skykryst profile image
Aakash Meshram

Next, the comments will be about solidjs

jack_garrus profile image
Nadia Guarracino

This is great! I always wandered what Preact was about and yout article was very useful! It seems perfect for my current project

nssimeonov profile image
Templar++ • Edited

Agree. Actually developers/companies who create browsers may eventually sober up and create some useful components and provide better means to validate so we don't have to reinvent the wheel in every framework and component library.

Date input was nearly unusable until a couple of years ago. It still sucks TBH.

Fixed table header was a thing for over a dekade. It still requires a considerable amount ot black magic.

Years ago I was working on a project and at this time chrome lacked the print preview and options dialog. Before developers released this feature, chrome got WebGL, WebSockets and whatnot, but printing was still waiting.

Firefox had an insanely useful plugin jsPrintSetup which no longer works. None of the browsers allows you to do some customizations to the page before printing something (like printing a barcode to a specialized label printer and the rest of the page on you regular one, like we did this with the old version of FF, all this with a single button click)

Recently I was offered to work on a project that was using Telerik's components, which by far are the biggest monstrosity I've ever met and surprisingly to me people are happily using them, and even more surprising to me users are patiently waiting for the page to appear and start working...

I can keep going on and on...

ivan_jrmc profile image
Ivan Jeremic

Speed is fine in React.

adhammoussa profile image
Adham Moussa

Thanks for the interesting post.
The performance comparison should also consider the change in performance metrics when the app gets more complex

cyrstron profile image

Performance is not the most important thing.

How about hooks? Can't see those in description.

rschristian profile image
Ryan Christian

Yes, hooks exist and work in Preact exactly as you'd expect, see docs

kaleabmelkie profile image
Kaleab S. Melkie

Can you compare it with Svelte now?

nilanth profile image

Will try it.

unscrambles profile image

I will try this, looking very interesting

kernel982 profile image
Dilshad Ahmed

Thanks for the post!
Will surely give Preact a try next!