from functools import wraps
from time import perf_counter_ns
 
def time_it(f):
    @wraps(f)
    def wrap(*args, **kw):
        ts = perf_counter_ns()
        result = f(*args, **kw)
        te = perf_counter_ns()
        print(f'func: {f.__name__} args: [{args}, {kw}] took: {(te - ts) / 1_000_000_000} sec.')
        return result
    return wrap
 
# A list of 100_000 dictionaries:
l = [{'v': 1} for _ in range(100_000)]
 
N = 300
 
@time_it
def test1():
    for _ in range(N):
        l_copy = list(d['v'] for d in l)
    return l_copy
 
@time_it
def test2():
    for _ in range(N):
        l_copy = [d['v'] for d in l]
    return l_copy
 
 
test1()
test2()

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