What would be most hard to calculate for computer?

What would be most system load? Case 1. Simple Math expression ((x^2) + (y^2)) that is called eventtick (only when i need) and does some calculation by incoming variables. Then results is compared to other variable. Case 2. We Have 2 actors and event beginoverlap. On begin overlap does some function. Subject is event beginoverlap and his calculate. So what the differences? I think that Case 2 would be harder to calculated. Because it’s comlpicated math than case 1. Am i right?