Why is string's startswith slower than in?

Question

Surprisingly, I find startswith is slower than in:

In [10]: s=\"ABCD\"*10

In [11]: %timeit s.startswith(\"XYZ\")
1000000 loops, be         


        

Answer 1

This is likely because str.startswith() does more than str.__contains__(), and also because I believe str.__contains__ operates fully in C, whereas str.startswith() has to interact with Python types. Its signature is str.startswith(prefix[, start[, end]]), where prefix can be a tuple of strings to try.