In [27]: %%timeit
...: x = int("7" * 100)
...: for i in range(1000):
...: x += x
...:
71.3 µs ± 624 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
In [28]: %%timeit
...: x = int("7" * 100)
...: for i in range(1000):
...: x += x
...: x %= 1000000007
...:
104 µs ± 890 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)