Obviously some fast compressors or fast mode are good at "size/orignal size * time "
Always it cost more folds of time to compress some folds of bytes.
Depends if the FS does copy as COW perhaps?
I think pigz is quite good
NTFS (LZSS) Windows built in compression is faster than copy (because of reduced disk access).
However on LTCB, lz4 0.2 beats it and zhuff 0.1 is a close second place ranked by smallest (compression time + decompression time)*size.