PyPy's JIT requires quite a bit of memory. CPython doesn't have a JIT so it doesn't share that problem. However PyPy also has optimizations specifically to keep

PyPy's JIT requires quite a bit of memory. CPython doesn't have a JIT so it doesn't share that problem. However PyPy also has optimizations specifically to keep memory usage down. Especially if you have a lot of objects, it's certainly possible to consume less memory than CPython. PyPy using less memory than Go does seem weird but depending on how much the GCs differ and how they are configured it could simply be that Go's GC doesn't give up memory as freely to the OS.