Android was designed when mobile GPUs were an oddity and stylus input was the norm. As such, rendering is mostly done in software and both redraw events and input are handled by the CPU. Mango and iOS were designed with hardware acceleration in mind, and render everything to 3D textures so they can use the GPU to get that smooth feel.

The ICS reveal later this month will reveal whether Google has addressed this issue. Most of Honeycomb is already GPU-accelerated, but not all of the performance issues were fixed.