reactRouterV6BrowserTracingIntegration perf issues with React 19.2 (development env only) #17888

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1. linear commented on Oct 8, 2025

   

   linearBot

   on Oct 8, 2025 – with Linear

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   JS-1034
2. scttcper

   added a commit that references this issue on Oct 8, 2025

   fix(sdk): Disable react rouer tracing integration in dev mode (#101169)

   ...

   286062e
3. billyvg commented on Oct 9, 2025

   

   billyvg

   on Oct 9, 2025

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   To repro, in the sentry repo:

   • revert this commit: git revert 286062e88765cec92c321e60afc161a97007c1ee
   • run pnpm dev-ui'
   • Go to the /replays/ page and click around, you'll notice that it's incredibly slow
4. Lms24

   self-assigned this

   on Oct 10, 2025
5. Lms24 commented on Oct 10, 2025

   

   Lms24

   on Oct 10, 2025

   Last edited by Lms24

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   After reproducing this, it appears to be caused by the SDK backfilling measure spans from React 19.2 now emitting custom tracks for component rendering time: https://react.dev/blog/2025/10/01/react-19-2#performance-tracks

   These are created via performance.measure() calls, which our SDK extracts and creates spans from when ending the idle span. This is pretty apparent when setting debug: true and observing thousands of these logs:

   Sentry Logger [log]: [Tracing] Finishing "measure" span "​Link" with ID 943626a659c8694f
   debug-logger.js:92 Sentry Logger [log]: [Tracing] Starting sampled span
     op: measure
     name: ​_c
     ID: 9ecdeabe9ead2784
     parent ID: 8601431d961d9cce
     root ID: 8601431d961d9cce
     root op: pageload
     root description: /issues/
   debug-logger.js:92 Sentry Logger [log]: [Tracing] Finishing "measure" span "​_c" with ID 9ecdeabe9ead2784
   debug-logger.js:92 Sentry Logger [log]: [Tracing] Starting sampled span
     op: measure
     name: ​Wrapper
     ID: bc3930cdd80a40a2
     parent ID: 8601431d961d9cce
     root ID: 8601431d961d9cce
     root op: pageload
     root description: /issues/
   
   ...
   

   We'll need to find a way to exclude these measure spans by default. This generates so many spans that the transaction gets dropped by Relay due to it exceeding the 1000 span limit. Gonna try to come up with a fix today.
6. Lms24

   closed this as completedin #17905on Oct 15, 2025
7. github-actions commented on Oct 15, 2025

   

   github-actionsBot

   on Oct 15, 2025 – with GitHub Actions

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   A PR closing this issue has just been released 🚀

   This issue was referenced by PR #17905, which was included in the 10.20.0 release.