Next.js 4 has been released with support for React 16, introducing a major upgrade for the default styling engine styled-jsx with dynamic styles. The new version features significant performance improvements, including SSR that is 2.6x faster and style initialization that is 20% faster than in previous versions. Next.js 4 is also more compatible with React 16, allowing developers to take advantage of numerous improvements introduced by the latest version of React. Additionally, styled-jsx 2 has been improved with support for dynamic styles, variables, and expressions from component props or state, reducing the need for inline styles in combination with static styles. The new release includes several minor changes and fixes, as well as a significant increase in contributors to the project, making it one of the most actively maintained open-source projects.