Runtimes often uses a lot of small malloc/free calls in quick succession. Since I worked with implementing a runtime at Google I've seen the function call overh

Runtimes often uses a lot of small malloc/free calls in quick succession. Since I worked with implementing a runtime at Google I've seen the function call overhead go up to 20% of the cost of it in real programs, since the actual memory needed was very small. You might argue that we should have done that optimization on our own, but we are just a small team doing an inhouse thing so we don't have those kind of resources, so to us it helps a lot that the the default malloc is very optimized.