[mrtksn]

Here is a video presentation from Apple about the topic: https://developer.apple.com/videos/play/wwdc2022/110362

It has an introduction section on what is a linker and why you need one. The gist is, linker is the piece of software that puts together different source file, be it at compile time or runtime. So, the faster is your linker the quicker the app compiles and opens.