__slots__ memory optimization in Python

#!/usr/bin/env python
import os, sys
from collections import namedtuple
from dataclasses import dataclass
from typing import NamedTuple

def get_process_rss():  # Similar to: psutil.Process().memory_info().rss / 1024 / 1024
    try:
        with open(f"/proc/{os.getpid()}/statm", encoding="utf8") as statm:
            rss_as_mib = int(statm.readline().split()[1]) * os.sysconf("SC_PAGE_SIZE") / 1024 / 1024
        return f"{rss_as_mib:.1f} MiB"
    except FileNotFoundError:  # /proc files only exist under Linux
        return "<unavailable>"

class A:
    def __init__(self, x, y, z):
        self.x = x
        self.y = y
        self.z = z

class B:
    __slots__ = ('x', 'y', 'z')
    def __init__(self, x, y, z):
        self.x = x
        self.y = y
        self.z = z

@dataclass
class C:
    x: int
    y: int
    z: int

@dataclass(slots=True)  # since Python 3.10, this is the same as defining __slots__ manually
class D:
    x: int
    y: int
    z: int

E = namedtuple('E', ('x', 'y', 'z'))

class F(NamedTuple):
    x: int
    y: int
    z: int

Class = locals()[sys.argv[1].upper()]
l = []
for _ in range(100000):
    l.append(Class(0, 1, 2))
print(get_process_rss())

$ ./slots_test.py a
26.6 MiB
$ ./slots_test.py b
17.2 MiB
$ ./slots_test.py c
26.7 MiB
$ ./slots_test.py d
17.2 MiB
$ ./slots_test.py e
19.1 MiB
$ ./slots_test.py f
19.2 MiB

$ ./slots_test.py a
28.3 MiB
$ ./slots_test.py b
22.0 MiB
$ ./slots_test.py c
28.3 MiB
$ ./slots_test.py d
22.0 MiB
$ ./slots_test.py e
24.8 MiB
$ ./slots_test.py f
24.2 MiB