When you cook a project for the first time you’re compiling all material shaders into a standalone executable that runs independently of the editor. More (and more complex) materials equals longer cooking time. Following standard best practices like using a few master materials with material instances will reduce cooking time. Cooking is basically the same thing as compiling and it’s not something that’s specific to Aximmetry. This is good news, since you should find a lot of information about this if you Google it. Here’s the official documentation to get you started: https://dev.epicgames.com/documentation/en-us/unreal-engine/packaging-and-cooking-games-in-unreal-engine