fix: Skip accept-language parsing when locale cookie is already present#2143
Merged
amannn merged 1 commit intoamannn:mainfrom Dec 1, 2025
Merged
fix: Skip accept-language parsing when locale cookie is already present#2143amannn merged 1 commit intoamannn:mainfrom
accept-language parsing when locale cookie is already present#2143amannn merged 1 commit intoamannn:mainfrom
Conversation
…arsing Previously, getAcceptLanguageLocale was called unconditionally, causing linear performance degradation with a large number of locales. This change lazy-evaluates the header parsing only when needed.
|
@lxup is attempting to deploy a commit to the next-intl Team on Vercel. A member of the Team first needs to authorize it. |
|
The latest updates on your projects. Learn more about Vercel for GitHub.
|
amannn
changed the title
accept-language parsing when locale cookie is already present
amannn
changed the title
accept-language parsing when locale cookie is already presentaccept-language parsing when locale cookie is already present
Contributor
Author
|
@amannn thx! That was my first PR ever 😅 |
This was referenced Dec 11, 2025
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #2116
Description
This PR addresses a severe performance bottleneck in the
syncCookiemiddleware logic wheregetAcceptLanguageLocale(and consequently locale negotiation) was called unconditionally on every request.As detailed in the linked issue, this caused linear performance degradation as the number of locales increased (~130ms overhead for ~140 locales).
Changes
I optimized the
syncCookiefunction to verify the cookie state before attempting to derive the locale from headers.Benchmarks
Tested with ~140 locales in the reproduction repository provided in the issue.
Before:
After:
Checklist