How can I see which i686 instructions are faster

Question

As the title says, I want to see which i686 instructions are faster, how can I see?

Example: is adding to a register faster or moving a value to a reg faster?

Answer 1

So I've read the begining of the pdfs from https://www.agner.org/optimize/, it is a pretty good source, there are in total 5 pdfs including cpp and asm optimization and instruction speed