Well not quite. The problem is that it only takes one call tree with a deep stack to cause all that memory to be allocated (slowly, using lots of page faults) a

Well not quite. The problem is that it only takes one call tree with a deep stack to cause all that memory to be allocated (slowly, using lots of page faults) and after that, it's used. The only way to get rid of it again is to swap it out, which means if you then go ahead and do another deep call it's even slower as the kernel doesn't know what it can discard and what it can't. Deep stacks are pretty common in modern software especially for Java software.