Exist a faster way to merge two deques than this?

# a, b are two deques. The maximum length 
# of a is greater than the current length 
# of a plus the current length of bwhile len(b):a.append(b.popleft())

Note that I'm not interested in preserving input deques, I'm only interested in having the merged one as fast as possible.

There's no need for elementwise appending, you can just use +=:

from collections import dequea = deque([1, 2, 3])
b = deque([4, 5, 6])a += bprint(a)deque([1, 2, 3, 4, 5, 6])