Faster, in what respects? You really can't compare a sports bike built for speed and the track, compared to a cruiser bike thats built for crusing the country.
That being said, either platforms can be built to be fast. There are fewer dragsters now days built on harley engines now that zuk's are almost everywhere. Even then, there are still a good number of buell drag bikes (harley engines) that pump 7 seconds or less in 1/4 mile. Now harley's aren't designed to be cornered on the track (cept for the buell, but they really don't count as being "harleys" since it was a different company that harley finally bought out, but used harley engines in sports bikes).
If you want a fair comparison, compare v-twin vs. I-4 engines of different sports bikes, like the sv650, but even then they are totally different bikes.