Apple launched macOS 10.13.5 developer beta 4 Tuesday, in accordance with iOS 11.4 developer beat 4. The biggest feature for end users is the ctinued testing of Messages in iCloud.
iCloud
This feature moves the local storage from iMessages to iCloud. Rather than telling everything locally and syncing everything when you use your individual Apple devices, these devices ly get recent iCloud messages.
If you have many chats and iMessages group chats, and if these cats are image, movie, or other heavy files, this will save you space. For example, my Messages folder is currently 11 GB and growing. This will also speed up synchrizati devices that you do not use every day.
Apple Developer Betas
Developers can set up their Macs the Apple Developer Cnecti. Macs that have been set up for the developer's beta program will find the update in the Mac App Store.