np.array большое потребление памяти

sql = pd.read_sql(f'SELECT...', con=engine)
a = []
a.append(sql[i:i+window])

np.array(a, dtype=np.float32)

df_n2=df.to_numpy()

df_n3=df.to_numpy(copy=True)

import numpy as np
import pandas as pd
import sys
lt=np.random.normal(size=1000)
df = pd.DataFrame({"A": lt, 
                   "B": lt,
                   "С": lt,})
print('df   :  ',sys.getsizeof(df))
 
df_n2=df.to_numpy()
print('df_n2: ',sys.getsizeof(df_n2))
 
df_n3=df.to_numpy(copy=True)
print('df_n2: ',sys.getsizeof(df_n3))

df   :   24144
df_n2:  120
df_n2:  120

lt2 = []
for i in range(100000):
   lt2.append(random.random())
print('lt2 :  ',sys.getsizeof(lt2))
 
np2=np.array(lt2)
print('np2   :  ',sys.getsizeof(np2))

lt2     :   800984
np2   :   800104

import numpy
import tracemalloc
 
 
tracemalloc.start()
print(tracemalloc.get_traced_memory())
 
a = [[[.0 for _ in range(20)] for _ in range(20)] for _ in range(20)]
 
print(tracemalloc.get_traced_memory())
tracemalloc.stop()
 
 
tracemalloc.start()
print(tracemalloc.get_traced_memory())
 
b = numpy.zeros((20, 20, 20), numpy.float16)
 
print(tracemalloc.get_traced_memory())
tracemalloc.stop()