This seems common but not a necessary property of course. If predictable performance was a design constraint, you could do it. And there's a spectrum between "m

This seems common but not a necessary property of course. If predictable performance was a design constraint, you could do it. And there's a spectrum between "maximally predictable" and "very unpredictable". Unpredictability could eg result in a need to more generous overprovisioning infrastructure and have less deterministic scaling, or some users having a game run slowly despite meeting hw requirements, so sometimes it might be good to have deterministic but bit slower on average execution.