The new feature in Xcode 16 called "explicitly built modules" enables faster compilation times by making builds more granular and allowing the build system to understand smaller tasks, thus improving efficiency. This results in fewer and longer build tasks compared to the traditional implicitly built module approach. The explicitly built module graph is more granular, revealing critical paths and dependencies between modules. While the initial release may show mixed performance results, this feature promises benefits such as deterministic builds, more informative error messages, and faster debugging in Xcode. The new feature can be enabled by default for C and Objective-C code or as a project-level setting for Swift code, with some potential drawbacks including reduced compilation speed initially and the possibility of multiple module variants being built.