Why is order of expressions in if statement important

Question

Suppose I have an IF condition :

if (A || B) 
    ∧
    |
    |
   left
{ 
   // do something  
}

Now suppose that A

Answer 1

Yes exactly, you're gaining runtime, it won't seem much for one operation, but you have to keep in mind that operations will get repeated millions of times

Why perform two evaluations when one is enough is the logic