Well CPython is an interpreter not a compiler so that's not really hard to do.

Not exactly. CPython combines a compiler and a bytecode interpreter. It compiles to bytecode, which is then run by the bytecode interpreter.

> Any weekend compiler project can be faster than CPython.

Not true and not even funny.

To write a compiler (and not a interpreter) it's indeed almost impossible to reach the slowness of CPython. Especially because it's hard to create a complex language in just a weekend.

using llvm as the backend not hard to make a toy language which runs insanely fast with only integer operations.

Exactly.