[Python] convert file to dict where value is a code, e.g. PovScore(1,2)

I have following data (7MB) and it's stored in transpostion.txt:

{'0x2df54c975eb48346': [PovScore(Cp(+57), BLACK), 5], ...}


I did try

with open("transposition.txt", "r") as file:
x = file.readline()
transposition = eval(x)
del x


but the memory reaches 99% and then hangs. I did try with 1MB file, it immediately loads and set the string, but when print it's very slow (IDLE):

>>> with open("testfile.txt", "r") as file:
x = file.read()

>>> x
Squeezed text (2000 lines)


json module can't parse JSON with code:

Traceback (most recent call last):
File "<pyshell#19>", line 1, in <module>
json.dumps({'a'ovScore(0,0)})
File "C:\Users\asdfs\AppData\Local\Programs\Python\Python39\lib\json\__init__.py", line 231, in dumps
return _default_encoder.encode(obj)
File "C:\Users\asdfs\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 199, in encode
chunks = self.iterencode(o, _one_shot=True)
File "C:\Users\asdfs\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 257, in iterencode
return _iterencode(o, 0)
File "C:\Users\asdfs\AppData\Local\Programs\Python\Python39\lib\json\encoder.py", line 179, in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type PovScore is not JSON serializable

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