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[Fiber] Bail out of diffing wide objects and arrays - #34742
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eps1lon merged 1 commit intoOct 5, 2025
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Has this made it into a release yet? |
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Fixesfirefox-devtools#6081. React 19.2 introduced diffing of component props, and puts the diff into the performance.measure detail object, which is super slow and makes memory usage and GC times blow up. There's a workaround on the 19.3 track but no 19.3 release yet. See react/react#34693 and react/react#34770 , with the workaround having landed in react/react#34742 .
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Fixes#6081. React 19.2 introduced diffing of component props, and puts the diff into the performance.measure detail object, which is super slow and makes memory usage and GC times blow up. There's a workaround on the 19.3 track but no 19.3 release yet. See react/react#34693 and react/react#34770 , with the workaround having landed in react/react#34742 . Co-authored-by: Nazım Can Altınova <canaltinova@gmail.com>
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Fixes#34693
When we commit in development, React will diff objects to check if they might be referentially equal and add a hint that the object should be memoized. If they're unequal, React will show a diff.
However, we attempted to diff the full object which can be problematic for wide objects or, like in the original report, large Arrays.
With this we just bail out after 100 properties. Ideally, we'd have different counters for how many properties we check and how many diffed properties we print. Checking 10k properties would make sense. Adding a diff for 10k properties does not.
Test plan