There's a ton of good technics to dive into, but in my mind it's almost all to address one leading sore point of containers:
With composefs, if two containers have the same file- wherever on the filesystem it is- that file will only be stored once on the host, and (equally if not more importantly) it will be shared in the page-cache (the cache for file contents). Currently, in most systems, different images end up having replicas of the same file that aren't shared on disk or in the page-cache.
If, for example, your org has a handful of base images it works from, it could drastically reduce the footprint of containers, both on disk and in memory. By effectively sharing the things that can be shared.
With composefs, if two containers have the same file- wherever on the filesystem it is- that file will only be stored once on the host, and (equally if not more importantly) it will be shared in the page-cache (the cache for file contents). Currently, in most systems, different images end up having replicas of the same file that aren't shared on disk or in the page-cache.
If, for example, your org has a handful of base images it works from, it could drastically reduce the footprint of containers, both on disk and in memory. By effectively sharing the things that can be shared.