What is the most scarce resource for average developer. Is it CPU? Is it memory? Is it network bandwidth? Or is it his own time? I guess for most developers it

What is the most scarce resource for average developer. Is it CPU? Is it memory? Is it network bandwidth? Or is it his own time? I guess for most developers it is reasonable to trade-off to blow few megabytes here and some kilobits there in order to save even few hours of precious calendar time. When everybody contributing to the dependency graph does that, it adds up.