Sort By .items() vs Sort By .keys()

perftest.py

import pprint
import random
import timeit

MEMBS_COUNT = 100

indexes = list(range(MEMBS_COUNT))
random.shuffle(indexes)

orig_dict = {}
work_dict = {}


def sort_items():
    sm = 0
    for sz, flist in sorted(work_dict.items()):
        sm += len(flist)
    return sm


def sort_keys():
    sm = 0
    for sz in sorted(work_dict.keys()):
        flist = work_dict[sz]
        sm += len(flist)
    return sm


results = {}
for iteration in range(5):
    print(f"Iteration #{iteration}")
    orig_dict = {i: [random.randint(0, 100) for _ in range(random.randint(2, 20))] for i in indexes}
    for fun in ["sort_items", "sort_keys"]:
        print(f"{fun}:\n  ", end="")
        # noinspection PyRedeclaration
        work_dict = orig_dict.copy()
        one_result = timeit.repeat(f"{fun}()", globals=globals(), number=100000)
        print(one_result)
        results.setdefault(fun, []).extend(one_result)

pprint.pprint(results)

result.txt

Iteration #0
sort_items:
  [2.2665747, 2.2948671, 2.2741954, 2.3581256, 2.246713099999999]
sort_keys:
  [1.6133939000000002, 1.5604682000000007, 1.5670964999999981, 1.5475289999999973, 1.5408910999999996]
Iteration #1
sort_items:
  [2.3382344999999987, 2.3232704999999996, 2.2793155000000027, 2.3203272000000013, 2.2972348999999994]
sort_keys:
  [1.6016799000000006, 1.4441036999999994, 1.5775312000000028, 1.604745600000001, 1.5907763000000017]
Iteration #2
sort_items:
  [2.322138899999999, 2.3223701000000005, 2.339320200000003, 2.2799884000000006, 2.3741212000000047]
sort_keys:
  [1.6397268999999994, 1.6084398000000064, 1.6292432999999988, 1.6413487000000018, 1.6348839999999996]
Iteration #3
sort_items:
  [2.3771400999999983, 2.349693700000003, 2.276641099999999, 2.284355000000005, 2.3402518000000043]
sort_keys:
  [1.5678709000000026, 1.6302175999999946, 1.5701210000000003, 1.6141111000000024, 1.6115692999999993]
Iteration #4
sort_items:
  [2.329644899999991, 2.29828950000001, 2.383834500000006, 2.3755140000000097, 2.368676999999991]
sort_keys:
  [1.6295487000000008, 1.6385052999999914, 1.6402142000000026, 1.6683847999999983, 1.713991699999994]
{'sort_items': [2.2665747,
                2.2948671,
                2.2741954,
                2.3581256,
                2.246713099999999,
                2.3382344999999987,
                2.3232704999999996,
                2.2793155000000027,
                2.3203272000000013,
                2.2972348999999994,
                2.322138899999999,
                2.3223701000000005,
                2.339320200000003,
                2.2799884000000006,
                2.3741212000000047,
                2.3771400999999983,
                2.349693700000003,
                2.276641099999999,
                2.284355000000005,
                2.3402518000000043,
                2.329644899999991,
                2.29828950000001,
                2.383834500000006,
                2.3755140000000097,
                2.368676999999991],
 'sort_keys': [1.6133939000000002,
               1.5604682000000007,
               1.5670964999999981,
               1.5475289999999973,
               1.5408910999999996,
               1.6016799000000006,
               1.4441036999999994,
               1.5775312000000028,
               1.604745600000001,
               1.5907763000000017,
               1.6397268999999994,
               1.6084398000000064,
               1.6292432999999988,
               1.6413487000000018,
               1.6348839999999996,
               1.5678709000000026,
               1.6302175999999946,
               1.5701210000000003,
               1.6141111000000024,
               1.6115692999999993,
               1.6295487000000008,
               1.6385052999999914,
               1.6402142000000026,
               1.6683847999999983,
               1.713991699999994]}