Parsing baseball files in Rust instead of Python for an 8x speedup

I see a number of micro-optimizations that may give you a few percent more in Python.

For example, you use GameSituation as a mutable way to maintain parse state. You modify it with things like "gameSituation.outs += 1".

Mutating instance attributes has a much higher overhead in CPython than in C/C++ (and presumably Rust). You can reduce some of that overhead by telling the class which slots to have.

Consider "spam.py" containing the following:

  class Foo:
    def __init__(self):
      self.a = 0

  class Bar(Foo):
    __slots__ = ("a",)

  % python -m timeit -s 'import spam; x=spam.Foo()' 'x.a = 3'
  5000000 loops, best of 5: 41 nsec per loop
  % python -m timeit -s 'import spam; x=spam.Bar()' 'x.a = 3'
  10000000 loops, best of 5: 32.4 nsec per loop

  % python -m timeit -s 'import spam; x={}' 'x["a"] = 3'

Another micro-optimization is to reduce the number of temporary strings. Consider:

     if (batterEvent.startswith('W+') or batterEvent.startswith('IW+') or batterEvent.startswith('I+')):
        tempEvent = batterEvent[2:]

     if batterEvent[i:i+2] in ("W+", "I+") or batterEvent[i:i+3] == "IW+":
        i += 2

(BTW, there appears to be a bug in your original code, since "IW+" is 3 letters long.)

Another BTW, you might change "for line in f.readlines()" to "for line in f". Shouldn't affect performance but should reduce your overall memory use.

In closing, character-level string processing in CPython is slow so I doubt you'll get all that much faster.

You might try pypy, but with the number of temporary strings you create, my guess is pypy still won't be that much faster. Should be easy to test though.