Apple highlighted two primary objectives for iOS 27: enhancing overall system performance and integrating AI capabilities through Apple Intelligence and updated Siri functionalities. While the AI features represent the most prominent additions, performance optimizations have yielded a significant benefit — Apple is maintaining compatibility across its entire iPhone lineup, including the iPhone 11, which launched in 2019. This means any device capable of running iOS 26 will also support iOS 27.
The specific optimization responsible for extending iPhone 11 compatibility remains unclear. However, Apple states that iOS 27 introduces substantial speed improvements, with apps launching up to 30% faster. Additional enhancements include a newly optimized CPU scheduler, contributing to the operating system’s improved efficiency. Despite these performance gains, the iPhone 11 and older models remain incompatible with Apple Intelligence features and the latest Siri AI capabilities, which require at minimum an iPhone 15 Pro or Pro Max.
This decision stands in contrast to Apple’s approach with other platforms. Meanwhile, watchOS 27 will only be available on Apple Watch Series 10 and newer, Apple Watch Ultra 2 and newer, and the Apple Watch SE 3 — effectively leaving behind several previous-generation models that supported watchOS 26.