Been playing SMS since the week it came out, no slowdown other than the seen with the red dudes on the mirrored dishes.
And no one is insulting the use of cel-shading or otherwise by stating which is easier to create textures for. The textures are simpler and the wire frames are more complex. We all know it takes more processing power many times. Both techniques, cel-shading and the normal method, are have their respective places. I would prefer my Bond games, Madden games, Mario games, and other such titles to be done the normal way. Zelda, RPGs, cartoon based titles or niche titles I like cel-shading. And of course, there are always cross-overs. My coding experience includes web-design and enough c to make a calculator, so I won't comment on that aspect. I simply feel they both have pros and cons, as well as their own difficulties.