Does extracting functions incur performance penalties?

Question

I am iterating through a large array (10^5 items) and performing an operation on each.

for (var row in rows) {
  switch (operator) {
    case "op1":
      row += 1;
      break;
    case "op2":
      ...
    case "opN":
      break;
  }
}

For testability and readability, I would like to extract that inner switch statement to it's own function, so the loop merely looks like

for (var row in rows) {
  this.updateRow(row, operator);
}

Will the overhead associated with calling a function 10^5 times cause a noticeable performance penalty?

Answer 1

Inline functions are always going to be a liiiitle bit faster than defined ones. This is because things like parameters and returns don't need to be pushed and popped from the stack at runtime. Usually this isn't much of an issue with newer machines, but with 10^5 function calls you could see a little bit of a performance hit.

I'd probably keep it inline. Doesn't really hurt much, and every little bit of optimization helps!