I think the main thing is to write the code as clearly as possible. Micro-optimizations like this shouldn't be the focus.
For example, if you have something like this:
if (age == 10) {
// ...
} else if (age == 20) {
// ...
} else if (age == 30) {
// ...
} else if (age == 40) {
// ...
}
Then it's clearer to use a switch statement:
switch (age) {
case 10:
// ...
break;
case 20:
// ...
break;
case 30:
// ...
break;
case 40:
// ...
break;
}
Again, I would focus on making the code easiest to read and maintain rather than nano-second level efficiency gains.