Python optimization problem

nice_but_slow.py

def validWylie(self, syllable):
    return syllable.wylie.startswith(self.ga_prefix) \
        or not any(char not in self.latin_set for char in syllable.wylie)

# called with: if not validWylie(somesyllable): ...
# runs at 10.7 seconds on test case

ugly_but_fast.py

def invalidWylie(self, syllable):
    if not syllable.wylie.startswith(self.ga_prefix):
         for c in syllable.wylie:
             if c not in self.latin_set:
                 return True

    return False

# called with: if invalidWylie(somesyllable): ...
# runs at 10.3 seconds on test case