Piccam has a smart "cache management" system that allows you to view your photos quickly without downloading them from the cloud. This also allows you to see your photos when you don't have WiFi or wireless connectivity. The cache uses a set amount of space dependent on the storage capacity of your device / phone.
If the device storage is less than 16GB, the cache can use up to 512 MB
16GB to 32 GB, the cache can use up to 1GB
32GB to 64GB, the cache can use up to 2GB
64GB to 128GB, the cache can use up to 4GB