i done some tests. on same storage ofcourse.
Transfer:
delta 1st full - 5.98 GiB (1min)
full no compression - 5.05 GiB (4min)
full zstd compression - 1.84 GiB (3min)
Indead looks weird. Time at least.
Im dunno if snapshot counts at that numbers, but it store on host storage anyway.
As for about space on storage itself, it can depend on thin\think, storage compression\dedup, block size, data blocks backup.