Earlier quoted context omitted.
The mainstream who shop at stores where every single appliance/device has "works with your iPod/iPhone!". The mainstream who go to hotels that have iPod docking stations in the room alarm clocks. The mainstream who go to fitness gyms that have iPod/iPhone docking stations in the workout equipment.
Ah, but you are conflating UI performance with something else. My point is, that UI performance is not an issue (at least hasn't been for a while). Other things, like high quality apps, ubiquitous docking stations in cars/hotels/..., on the other hand are quite important. That is, for vast majority of users, geeks who type 40+ words/minute on miniature screens don't count.
My position is that "mainstream" users - the type of people who care about the apps, docking stations, ubiquity of the platform, etc - also care about UI fluidity.