This also has to do with the available RAM. Floor model iPad's in my mind are not good benchmarks for anything unless you kill all the running apps, do a fresh reboot...etc.
I was just playing with my iPad2 and noticed some safari issues. I opened zTools and noticed I had about 35mb of the 500mb it was reporting free. Cleared my running apps, it jumped to almost 300mb, and safari was running very nice!
Yup, despite what Apple says about what apps in the multi tasking tray do or don't do in the background in terms of taking up resources, they definitely have an impact. I keep my tray as empty as reasonable and it makes a (positive) difference.