When Manipulating Lists in Python, Why is pop Slower than del?

Problem scenario
You use del and pop to remove items from lists. You noticed that pop is slower than del. Why is this the case?

Solution
There are two reasons. One, pop returns the value that is removed. Two, pop acts as a function call as opposed to a primitive action. Whereas the del invokes a primitive action (a non-recursive function call), pop involves recursion.

Basically, another operation has to take place with pop compared to del.

This program will have three function calls. If you run this program, you will see the number of function calls because we import cProfile and use it:

import cProfile
a = 1, 2, 3, 4, 5
contintlist = list(a)
cProfile.run('del contintlist[3]')

This program will have four function calls:

import cProfile
a = 1, 2, 3, 4, 5
contintlist = list(a)
cProfile.run('contintlist.pop(3)')

You can run the above programs to see for yourself.

This program prints out "4":

a = 1, 2, 3, 4, 5
contintlist = list(a)
x = contintlist.pop(3)
print(x)

This next program is very similar, but it does not run:

a = 1, 2, 3, 4, 5
contintlist = list(a)
x = del contintlist[3]
print(x)

This program will print out something like this:

File "t.py", line 3
     x = del contintlist[3]
           ^
 SyntaxError: invalid syntax

You see that pop does a return which is an additional function (as the profiler output of the first two programs will show). The del invocation is faster, but it returns nothing.