Your password is "validated" when created. Validation means checking if it contains (it has to to validate):
- a alpha character in it
- a numeric character in it
- a special character in it
- (maybe more, this list is from memory)
This means if you want to brute force such a password you do not need to check any password that does not follow the above mentioned rules. This makes the search space smaller and the cracking of the password faster.