You can create a package by choosing File > New Project … from the main menu, then Package… in the resulting dialog.

Ah, that's frustrating. It would be helpful if you could file a feedback with a CPU sample of AssetCatalogSimulatorAgent You can get a CPU sample either from activity monitor, or by running this in the terminal just before building. sample AssetCatalogSimulatorAgent 120 -wait Does the performance of the build change if you remove all of the groups and layers from the icon?