Instead of computing nA = A + A + … + A you can use the “exponentiation” by squaring trick: nA = (n/2)A + (n/2)A + (n%2)A. It takes logarithmically many steps.
Anyone know of an accessible intermediate resource on ECC? There are many blogs talking about the basics of point addition , but hardly anything approachable that talks about different curve properties, what makes a curve safe, how to break vulnerable curves, and how to prove properties, etc.