Apologies for the confusion. The comparison was against a new-style class as described in the original post. All of the types have two ints. The code is now linked so you can inspect and respond.

Edit to respond to edit: Built-ins and slots are even faster but the key point is that the ctypes-based class is actually slower than simply using a class with ordinary Python variables.

The reason ctypes is slower is that addition isn't defined on c_ints which requires casting them back to Python ints for each operation. This can be avoided by using ctypes to call a C function to perform addition.