Salted SHAx passwords are basically the entire reason GPU John The Ripper and oclHashcat exist, although SHA2-512 is significantly slower than SHA2-256, so if you're going to use a terrible SHA-based password hash, SHA2-512 is your best bet.
It'll (theoretically) be faster on any hardware that supports 64 bit operations, as SHA512 ends up doing fewer block operations.
This assumes you're hashing something at least 8 bytes long, and that your hash implementation is smart enough to use the 64 bit capabilities of your platform.