Why are more frequent snapshots or EBS Volumes faster?

Why are more frequent snapshots or EBS Volumes faster?

A.
Blocks in EBS Volumes are allocated lazily, since while logically separated from other EBS Volumes, Volumes often share the same
physical hardware. Snapshotting the first time forces full block range allocation, so the second snapshot doesn’t need to perform the
allocation phase and is faster.

B.
The snapshots are incremental so that only the blocks on the device that have changed after your last snapshot are saved in the new
snapshot.

C.
AWS provisions more disk throughput for burst capacity during snapshots if the drive has been pre-warmed by snapshotting and
reading all blocks.

D.
The drive is pre-warmed, so block access is more rapid for volumes when every block on the device has already been read at least
one time.

Explanation:
After writing data to an EBS volume, you can periodically create a snapshot of the volume to use as a baseline for new
volumes or for data backup. If you make periodic snapshots of a volume, the snapshots are incremental so that only the
blocks on the device that have changed after your last snapshot are saved in the new snapshot. Even though snapshots
are saved incrementally, the snapshot deletion process is designed so that you need to retain only the most recent
snapshot in order to restore the volume.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-creating-snapshot.html