perf: improve next server static performance

[SukkaW]

Previously, the serve-static utility function in Next.js would determine which codepath to use based on the version of mime for every incoming request. The PR changes so that the codepath will be determined in advance, thereby reducing the overhead.

[vercel]

Notifying the following users due to files changed in this PR based on this repo's notify modifiers:

@timneutkens, @ijjk, @shuding, @huozhi:

packages/next/src/server/serve-static.ts

[vercel]

Notifying the following users due to files changed in this PR based on this repo's notify modifiers:

@timneutkens, @ijjk, @shuding, @huozhi:

packages/next/src/server/serve-static.ts

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
buildDuration	14s	13.7s	N/A
buildDurationCached	8.5s	6.4s	N/A
nodeModulesSize	199 MB	199 MB	N/A
nextStartRea..uration (ms)	405ms	405ms	✓

Client Bundles (main, webpack)

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
2453-HASH.js gzip	31.4 kB	31.4 kB	N/A
3304.HASH.js gzip	181 B	181 B	✓
3f784ff6-HASH.js gzip	53.7 kB	53.7 kB	✓
8299-HASH.js gzip	5.04 kB	5.04 kB	N/A
framework-HASH.js gzip	45.2 kB	45.2 kB	✓
main-app-HASH.js gzip	242 B	241 B	N/A
main-HASH.js gzip	32.2 kB	32.2 kB	N/A
webpack-HASH.js gzip	1.68 kB	1.68 kB	N/A
Overall change	99 kB	99 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
_app-HASH.js gzip	196 B	197 B	N/A
_error-HASH.js gzip	184 B	184 B	✓
amp-HASH.js gzip	505 B	505 B	✓
css-HASH.js gzip	324 B	325 B	N/A
dynamic-HASH.js gzip	2.5 kB	2.5 kB	N/A
edge-ssr-HASH.js gzip	258 B	258 B	✓
head-HASH.js gzip	352 B	352 B	✓
hooks-HASH.js gzip	370 B	371 B	N/A
image-HASH.js gzip	4.21 kB	4.21 kB	✓
index-HASH.js gzip	259 B	259 B	✓
link-HASH.js gzip	2.67 kB	2.67 kB	N/A
routerDirect..HASH.js gzip	314 B	312 B	N/A
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	6.57 kB	6.57 kB	✓

Client Build Manifests

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
_buildManifest.js gzip	481 B	484 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
index.html gzip	529 B	529 B	✓
link.html gzip	541 B	541 B	✓
withRouter.html gzip	524 B	524 B	✓
Overall change	1.59 kB	1.59 kB	✓

Edge SSR bundle Size

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
edge-ssr.js gzip	95.4 kB	95.4 kB	N/A
page.js gzip	3.06 kB	3.06 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
middleware-b..fest.js gzip	626 B	623 B	N/A
middleware-r..fest.js gzip	151 B	151 B	✓
middleware.js gzip	25.5 kB	25.5 kB	N/A
edge-runtime..pack.js gzip	839 B	839 B	✓
Overall change	990 B	990 B	✓

Next Runtimes

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
app-page-exp...dev.js gzip	170 kB	170 kB	✓
app-page-exp..prod.js gzip	97 kB	97 kB	✓
app-page-tur..prod.js gzip	98.8 kB	98.8 kB	✓
app-page-tur..prod.js gzip	93 kB	93 kB	✓
app-page.run...dev.js gzip	144 kB	144 kB	✓
app-page.run..prod.js gzip	91.5 kB	91.5 kB	✓
app-route-ex...dev.js gzip	21.4 kB	21.4 kB	✓
app-route-ex..prod.js gzip	15.2 kB	15.2 kB	✓
app-route-tu..prod.js gzip	15.2 kB	15.2 kB	✓
app-route-tu..prod.js gzip	14.9 kB	14.9 kB	✓
app-route.ru...dev.js gzip	21.1 kB	21.1 kB	✓
app-route.ru..prod.js gzip	14.9 kB	14.9 kB	✓
pages-api-tu..prod.js gzip	9.55 kB	9.55 kB	✓
pages-api.ru...dev.js gzip	9.82 kB	9.82 kB	✓
pages-api.ru..prod.js gzip	9.55 kB	9.55 kB	✓
pages-turbo...prod.js gzip	22.5 kB	22.5 kB	✓
pages.runtim...dev.js gzip	23.1 kB	23.1 kB	✓
pages.runtim..prod.js gzip	22.4 kB	22.4 kB	✓
server.runti..prod.js gzip	51.1 kB	51.1 kB	✓
Overall change	945 kB	945 kB	✓

build cache

	vercel/next.js canary	SukkaW/next.js perf-next-image-response	Change
0.pack gzip	1.58 MB	1.58 MB	N/A
index.pack gzip	106 kB	106 kB	N/A
Overall change	0 B	0 B	✓

Diff details

Diff for middleware.js

Diff too large to display

Commit: 503f2da

[shuding]

Curious about the RPS differences!