Really? The only time I see anything close to a leak is when I look at the speed of various operations (and let's be honest, von Neumann's machines always had bottlenecks, as much as he tried to keep them out)
As soon as you run more than one thread, you'll have to worry about memory barriers, cache coherency, processor affinity etc. Even with one thread, modern IO and system calls are highly asynchronous. Not the sort of machine that e.g. C or C++ was originally envisioned for.
