Efficiency of using a Python list as a queue

Question

A coworker recently wrote a program in which he used a Python list as a queue. In other words, he used .append(x) when needing to insert items and .pop(0)

Answer 1

You won't run out of memory using the list implementation, but performance will be poor. From the docs:

Though list objects support similar operations, they are optimized for fast fixed-length operations and incur O(n) memory movement costs for pop(0) and insert(0, v) operations which change both the size and position of the underlying data representation.

So using a deque will be much faster.