I have absolutely no idea how HN replies work, but this is in response to the PyPy memory usage.
I'm optimizing for my application. If you want to use PyPy, use it. I couldn't care less.
If I was having a hard time already maxing CPU due to memory constraints, how does switching to something that will use a very large amount of memory (relative to the CPU gains) make any sense at all? Do you really think "more complex code" is going to use less memory?
If you want benchmarks, go find some, or go create some. It has absolutely nothing to do with the gains I'm pointing out by simple webserver choices and minor tuning.