import pickle

data = {
    i: str(10000 - i) for i in range(10000)
}

data[1] = [chr(i) for i in range(127)]

with open('data1.pickle', 'wb') as file:
   pickle.dump(data, file, protocol=None)

with open('data2.pickle', 'wb') as file:
   pickle.dump(data, file, protocol=4)

$ ls -sh *.pickle
168K data1.pickle  100K data2.pickle