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Kyle Hoskins
Kyle Hoskins

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How Next.js 12 improved Material-UI app compile by 8X

Some are calling Next.js 12 the "biggest step forward yet." Especially Rust fans.

Next.js 12's new Rust compiler features ~3x faster refresh locally and ~5x faster builds, but that's not the feature that helped me.

The unsung hero of the release for me was...

Compiled module count!

Next.js now outputs Fast Refresh timing in the console for both client and server compilation, including the number of modules and files compiled.

Image description

10,000 Modules * faint *

10,000 is great if we're talking about Outliers 📚, but downright scary 😱 when we're talking about modules.

My application uses Material-UI, but is pretty small, so what happened?!

Take a look:

import Menu from '@mui/icons-material/Menu';
import ChevronRight from '@mui/icons-material/ChevronRight';
import Save from '@mui/icons-material/Save';
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import { Menu, ChevronRight, Save} from '@mui/icons-material';
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The shorter one sure looks prettier, and VSCode even suggests importing from @mui/icons-material first, but don't fall for it!

How does it impact the compile time?

// importing from @mui/icons-material
event - compiled successfully in 5.1s (10013 modules)

// importing from @mui/icons-material/ChevronRight
event - compiled successfully in 615ms (1024 modules)
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As a first time Next.js user, I did not have a project to compare against to recognize that my compile times were slow until the new module count logging feature.

If you use Material-UI, be sure to replace any instances of direct imports from @mui/material or @mui/icons-material as you will be compiling ALL the modules from the entire packages. Watch out for barrel files too!

With 1,000 modules remaining, I still have some improvements to make, but I figured I'd share for any others who may experience the same shock! How many modules does your Next.js application have?

P.S. Thanks for reading my first DEV article!

Top comments (6)

jarraga profile image
Jorge Arraga

I came to this article because I had the same problem, it was a single line, I can't believe it... thank you so much! ✨

ruiguilherme profile image

Is this not a problem with SWC? babel doesn't have this kind of problem because of babel-plugin-transform-imports.

Look this:

atemiz profile image
Ahmet Temiz

I'm using top level imports with babel-plugin-import as described in the official docs.

kyleapex profile image
Kyle Hoskins

Thanks for sharing! I didn’t know about that, and it looks like a great solution. Going to try it later this weekend!

Sloan, the sloth mascot
Comment deleted
kyleapex profile image
Kyle Hoskins • Edited

Thanks for replying @rangercoder99 . What does “No it does not” refer to?

Starting from the third sentence, you will notice that this article is not about the Rust compiler, but that is good to know about the emotion package.