accelerate re-syncing for a large file (> 3 TB) with rsync

How to accelerate re-syncing large file (>3 TB) which got few of its blocks changed (< 1 GB) with rsync.

AFAIK, rsync will do checksum comparison between src/dst blocks to find the differences and then sync them.

Is there a way to increase concurrency at the checksum comparison stage to accelerate the sync?