I think people that use iPhone's before switching to Android spend so much time convincing themselves that Android is crap/slow/laggy. It's a self fulfilling prophecy.
My SO has a G2 (and it's not rooted) and it is just as "smooth" as my 5c.Comical!
I'm going to have to disagree with you here.. I recently aquired a galaxy s5 (I buy and sell phones locally) and I decided to give it a chance becuase honestly the screen was gorgeous! the initial honeymoon period was AWESOME. I was like...this phone rocks! After about a week the gimicks wore off and I started to notice things that bothered me personally. I would go to show someone a photo I took (something the s5 did better than any phone I've ever had) any the gallery took something like 5 seconds to open.. same with launching the camera from the lockscreen. It was a serious disappointment. I went back to my 5s and felt right at home. things really do open much quicker on the 5s. I think the days of "lag" when switching from homescreen to homescreen are over but the sttuter you get when opening apps and or closing apps is still very much a problem with today's flagship phones. And before you ask, I did have art enabled on my s5 and I did turn the annamation speed up. Something I dont think should be needed.