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Adlai Holler
4ac42d88ef
Summary: Few issues I saw when profiling RNTester: - Repeatedly calling `-lowercaseString` during `weightOfFont` causes a TON of extra memory traffic, for no reason. - `NSCache` is thread-safe, so no need for a mutex. - Using `stringWithFormat:` for the cache key is slow. Use `NSValue` to store the data directly instead. - Calling `-fontDescriptor` in `isItalicFont` and `isCondensedFont` is overly expensive and unnecessary. - `+fontNamesForFamilyName:` is insanely expensive. Wrap it in a cache. Unscientific test on RNTester iPhone 11 Pro, memory & time. Before: <img width="1656" alt="Screen Shot 2021-06-23 at 7 40 06 AM" src="https://user-images.githubusercontent.com/2466893/123092882-f4f55100-d3f8-11eb-906f-d25086049a18.png"> <img width="1656" alt="Screen Shot 2021-06-23 at 7 41 30 AM" src="https://user-images.githubusercontent.com/2466893/123092886-f6267e00-d3f8-11eb-89f6-cfd2cae9f7b6.png"> After: <img width="1455" alt="Screen Shot 2021-06-23 at 9 02 54 AM" src="https://user-images.githubusercontent.com/2466893/123101899-7d2c2400-d402-11eb-97f8-2ee97ee69ec4.png"> <img width="1455" alt="Screen Shot 2021-06-23 at 8 59 44 AM" src="https://user-images.githubusercontent.com/2466893/123101892-7bfaf700-d402-11eb-9a10-def46b37b87f.png"> Changelog: [iOS][Changed] - Optimized font handling Pull Request resolved: https://github.com/facebook/react-native/pull/31764 Reviewed By: appden Differential Revision: D30241725 Pulled By: yungsters fbshipit-source-id: 342e4f6e5492926acd2afc7d645e6878846369fc
