Did you try researching this at all by yourself? There are a plethora of blog posts explaining exactly what you are asking. Or you could go read the original paper. This would be easy enough to write a test script as well to empirically discover the answer.

With python and going from memory, bcrypt set for 12 rounds takes about .3 seconds on my laptop to compute a hash. I can compute hundreds of thousands of SHA512 hashes in that same amount of time.

Edit: And theoretically, you could make a SHA hash function that ran quite slowly, but why not just use bcrypt at that point.