What is the difference between responsive design and adaptive design in mobile performance optimization?

When optimizing mobile performance, the core difference between responsive design and adaptive design lies in their layout adaptation methods and resource loading strategies. Responsive design achieves "one codebase for multiple devices" through CSS media queries and fluid layouts, while adaptive design predefines multiple fixed layouts and matches the corresponding version based on device characteristics. The performance optimization focus of responsive design is **dynamic adaptation cost**: it needs to handle CSS rules for different screen sizes, which may increase the CSS file size due to a large number of media queries; resources such as images need to be conditionally loaded through srcset or picture elements, and improper configuration can easily lead to resource waste. The performance optimization of adaptive design focuses on the **precision of predefined layouts**: it loads the corresponding fixed layout after detecting the device via server or client, reducing dynamic client-side calculations, but may cause code redundancy and increased maintenance costs due to too many layout versions. In practical applications, for performance-priority scenarios (such as low-bandwidth environments), adaptive design can be considered to reduce client-side processing pressure; when pursuing development efficiency and multi-device flexibility, responsive design combined with resource compression (such as image lazy loading and CSS minification) is more suitable.