According to my measurements and to [this work](https://www.ucalgary.ca/pst2017/files/pst2017/paper-39.pdf), it seems that operations, for example scalar multiplication, are more expensive in larger groups. If I have, for example, an 80-bit elliptic curve and an 384-bit elliptic curve, then the difference is very big:

* 80-bit curve: 10ms per 1 multiplication on average
* 384-bit curve: 501ms per 1 multiplication on average

I don't know if it's related, but the method for multiplication is probably wNAF.

Question: Why basic operations are more expensive on larger groups?