Content caching
>If you have more than one Mac or iOS device, you can use a service called Content Caching to reduce the amount of data you download over the internet and speed up OS updates and the retrieval of other data. With Content Caching set up, whenever a Mac or iOS device on the network downloads an update, the update is stored on a Mac on the network. The next time a device requests the update, it’s delivered from the cache, rather than being downloaded again. And it’s not just OS updates. Content Caching supports apps, app data, such as GarageBand songs, Books, and iCloud data like photos and documents.
To switch it on, go to System Prefs > Sharing and check the box next to Content Caching. You can choose to cache all data, just apps and updates, or just iCloud data. Select Options to specify a limit for the amount of disk space it uses. You’ll need to restart devices so they can use Content Caching.