Since you brought up loading faster (mobile or otherwise really), just run your images with either PNGGauntlet or Trimage. They both basically do the same thing and it won't degrade the quality one bit (every pixel is identical). But your images will be smaller, thus loading faster and also requiring less RAM (more an issue for game images but still nice) as a result of being indexed (instead of 32bit RGB) and otherwise compressed. In some cases, it will be a little smaller, and in some cases MUCH smaller. But always smaller.
Both programs are ridiculously easy to use. You can browse to the file, but the easier thing is dragging the folder itself onto the program. And with that it loads them all (even recursively). Trimage instantly gets to work. PNGGauntlet requires you to hit the optimize button. Let it do its thing while you go microwave a burrito or something. That's all you do, and your files are smaller when it is done. It can't be said to require effort, which is nice.