Example
The %timeit magic runs the given code many times, then returns the speed of the fastest result.
In [1]: %timeit sum(range(100000))
100 loops, best of 3: 2.91 ms per loop
The %%timeit cell magic can be used to time blocks of code.
In [2]: %%timeit
...: a = 0
...: for i in range(100000):
...: a += i
...:
100 loops, best of 3: 9.67 ms per loop
The %time magic times a single run of a function, similar to the Unix time command. Unlike %timeit, %time also shows the result.
In [3]: %time sum(range(100000))
CPU times: user 2.68 ms, sys: 3 µs, total: 2.68 ms
Wall time: 2.69 ms
Out[3]: 4999950000
