On my SSD imaging (Source and Destination are 2 SSDs) I get 12GBpm using CloneZilla while with dd I get only 5GBpm.
What makes Clonezilla so much faster than dd?
dd just reads from block 0 to block 99999 and copies the data.
Clonezilla understands filesystems and understands when there is nothing to be copied (because that's empty space or data from a file that's been deleted).
Once you know not to copy all the useless data, it is much easier to copy the real data.
From the web page "For unsupported file system, sector-to-sector copy is done by dd in Clonezilla."
Well, that depends on what Clonezilla uses to do the cloning.
It uses different tools depending on the type of partition, taken from their website:
It will use them in that order typically to try and copy your partition. dd is a last resort because it is just sector by sector copying and does not have any optimization built in that would be based on the filesystem type of the partition. For example, cloning an ntfs partition would be a lot fast than cloning a hfs partition (at least with an older version of clonezilla, haven't used it in a while) because there was no built in tool for efficient hfs+ copying, and it used dd.