I'm a bit sceptical about the comparison of optimisation. Specifically when the AST was mentioned (did they parse the expression as Python code?) and Python came out that much slower even after fixes. As long as they were interpreting that, rather than compiling the expression into native code, I don't see a good reason for Go to be faster. Interpreting expressions like that in Go would be almost as dynamic / lookup heavy as in Python.

I'd like to see both apps for comparison / more context.