Cheng Lou(@_chenglou):The premature optimization of splitting animation work onto another process has done lots of harm to iOS (and web). For a brief while things were slightly smoother, but in exchange we ended up with uninterruptible animations and layout glitches from introducing unsolvable concurrency problems, plus various patches on top that ultimately make the system actually slower than if we just did things cleanly on main thread (or had access to proper multithreading in userland). Most tasteful UX cannot be decoupled in a computer sciency way Smooth animations in general are great but calcifying the rendering pipeline for a decade is a huge cost

2026.09.16 02:17

The premature optimization of splitting animation work onto another process has done lots of harm to iOS (and web). For a brief while things were slightly smoother, but in exchange we ended up with uninterruptible animations and layout glitches from introducing unsolvable concurrency problems, plus various patches on top that ultimately make the system actually slower than if we just did things cleanly on main thread (or had access to proper multithreading in userland). Most tasteful UX cannot be decoupled in a computer sciency way Smooth animations in general are great but calcifying the rendering pipeline for a decade is a huge cost

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