[Python] Efficient use of constants in multiple class instances

Class A has some methods where constant values are needed. Assuming multiple instances of class A need to be created, which option would be more efficient/cleaner?

Option 1 (constants outside of class):

CT_A = 1.0
CT_B = 2.0
...

class A:

def __init__(self):
...

def method_class(self):
return CT_A * (CT_B + 10.0) # Simple example of constant use


Option 2 (constants inside of class):

class A:

CT_A = 1.0
CT_B = 2.0

def __init__(self):
...

def method_class(self):
return self.CT_A * (self.CT_B + 10.0) # Simple example of constant use


Option 3 (Class inheritance):

class Constants:
CT_A = 1.0
CT_B = 2.0

class A(Constants):

def __init__(self):
...

def method_class(self):
return Constants.CT_A * (Constants.CT_B + 10.0) # Simple example of constant use


Code optimization is an issue in the project I need to implement this on as class A is a class to be used for several unit tests, hence the need to reduce computational cost.

In reality there are 5 or 6 constants, not just one or two as in this example.

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