I am not familiar with this particular product but generally if you run on say AWS you either need to account for the greatly increased disk latency due to EBS being network storage or build provisions for local storage that is not necessarily unlimited, it is unclear what kind of disk controller it is attached to, etc. It could also mean optimizing for the AWS-specific CPU architecture. Or it could mean using S3 as storage which has yet different durability and consistency semantics compared to other storage systems. It might also mean optimizing for pricing of a given cloud provider in some way.