If you want to try another launcher, like Apex
, you will probably see most of your lag disappear. I think most of the problem is TouchWiz needs to be optimized or something. Although I don't really experience real lag with TouchWiz, just a quick hesitation now and then.
With Apex, I experience zippity-doo-dah smoothness. The only problem is some of the widgets won't work the same in Apex, like the weather widget.