def accessdict(a, key1, key2):
    a[key1]
    a[key1]
    a[key2]
    a[key1]
    a[key1]
    a[key1]
    a[key2]
    a[key2]
    a[key1]
    a[key2]
    a[key1]
    a[key1]
    a[key1]
    a[key1]
    a[key1]
    a[key1]
    a[key2]
    a[key2]
    a[key1]
    a[key1]
    a[key1]
    a[key2]
    a[key1]
    a[key1]
    a[key1]
    a[key1]
    a[key2]
    a[key2]
    a[key2]
    a[key1]
    a[key2]
    a[key1]

class StrSub(str): __slots__ = ()

def main():
    from time import sleep
    from timeit import timeit
    ts = [[],[],[]]

    vx1 = 'x'
    vx1 += '1'
    cx1 = StrSub('x1')
    for i in range(100):
        adict = {'x1': 42, 'x2': 43, 'x4': 44}
        ts[0].append(timeit(lambda: accessdict(adict, vx1, 'x2')))
        ts[1].append(timeit(lambda: accessdict(adict, cx1, 'x2')))
        ts[2].append(timeit(lambda: accessdict(adict, vx1, 'x2')))
    for tt in ts:
        avg = sum(tt) / len(tt)
        sd = sum((v - avg)**2 for v in tt) / (len(tt) - 1)
        print(avg, '+-', sd**0.5)

main()