For freeze / restore : I just tried, it's a great fonctionnality.

For the scale : the GBA resolution is 240 x 160. So I imagine you've made a x2 ratio for the N810 screen, to get 480 x 320. Is another zoom factor possible (like 2.5 => 600 x 400) without a huge load on CPU, and without too much interpolation artefacts ?