How to reduce ram/resource usage and speed up game?

I’m trying to make my game use less resources and run faster for users who have slow computers.
I’m wondering if adding multiple times TimeDelta() to a variable costs more resources than adding the number 1 multiple times. In this case I would add 1 instead and then at the end multiply by TimeDelta().
Also I’m looking for any other advise. I have a lot of mathematical formulas. I have been using polynomials instead of functions such that exp or sqrt that cost more in term of computations.