Unlike hash operations, elliptic curve operations have unpredictable machine cycle count.
I would expect a single point addition operation (P
3 = P
1 + P
2) to have a very predictable machine cycle count. It should be something like:
x
3 = λ
2+a
1λ−a
2−x
1−x
2y
3 = −a
1x
3−a
3−λx
3+λx
1−y
1λ = (y
2−y
1) / (x
2−x
1)
From:
https://crypto.stanford.edu/pbc/notes/elliptic/explicit.htmlI did use that EC point increment method, otherwise the program would be 20x slower. Those multiplications/divisions are modulus but not conventional integer operators; they don't have predictable machine cycle count.