I mean if you want to upload 100Kb in SV you need 1tx : 200bytes of signature and 100Kb of data
In bch you'll have to do a lot of txs to split the 100Kb, and therefore lot of 200b sigs
Same way here I did 2txs to answer you because messages are short so I had to sign 2txs, that's 400bytes of signatures
For large uploads it multiplies the fees by ~1.5 I guess
