I've just tested that and you are correct, Pulse is a tad smoother on the Nexus. It doesn't launch as quickly though, the only instance where the applications perform the same are the Google ones, games and most third party apps are all quite a bit quicker on the S3.
There is no lag on the home screens though, absolutely none at all (there isn't on the Nexus either).
The stock browser on the Nexus seems to be quicker than the S3 as well, but I need to test that out a bit more... very impressive if so.