python - Why is list() 3 times slower than []

I just checked the difference of speed between list() and [], and was surprised to see that list() was 3 times slower than [] for list creation. I tested this in ipython with %timeit magic.

In [1]: %timeit a=list()

10000000 loops, best of 3: 67.5 ns per loop
In [2]: %timeit b=[]
10000000 loops, best of 3: 21.9 ns per loop

Then I thought maybe something is not happening until we actually put an element into it, so I tested the following.

In [3]: %timeit list().append(1)
10000000 loops, best of 3: 143 ns per loop


In [4]: %timeit [].append(1)
10000000 loops, best of 3: 88.7 ns per loop

Now the relationship changed, so then I tested only the appends.

In[5]: a=list()
In[6]: b=[]
In [7]: %timeit a.append(1)
10000000 loops, best of 3: 49.8 ns per loop

In [8]: %timeit b.append(1)
10000000 loops, best of 3: 54.2 ns per loop

What kind of sorcery is this? Why aren't the lists and the appends equivalent?