fix: use centralized cache for usePrefersReducedMotion hook#468
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mdjastrzebski wants to merge 2 commits intofacebook:mainfrom
Open
fix: use centralized cache for usePrefersReducedMotion hook#468mdjastrzebski wants to merge 2 commits intofacebook:mainfrom
usePrefersReducedMotion hook#468mdjastrzebski wants to merge 2 commits intofacebook:mainfrom
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Fix a performance issue in RN, when each RSD component (div, span, button, etc) calls
AcessibilityInfo.isReduceMotionEnabledon mount due tousePrefersReduceMotionhook called from styles calculation.This is especially visible on Android, where a single call is relatively cheap (0,1-0,3 ms), but with larger (e.g. 1000) number of components, this operation alone could take ~300ms in our app during screen load.
The fix is to keep a reactive JS cache for this value, so that only single
AcessibilityInfo.isReduceMotionEnabledis ever made, all other components would use the cached value. The cache itself subscribes toreduceMotionChangedevent, hence the value stays up to date.Additionally, having up-to-date value, prevents effect triggered re-renders when default value would switch to true.