I am in love!! My childen love to design art digitally, yet we all hate the resources that the larger editing software use. Today, while surfing Common Sense Media (an awesome website to check other parents ratings on websites, books, games and more) I ran across Sumo Paint. Sumo Paint has both a free option and a pro option. I haven't tried the Pro as the free version is more then enough to meet our family's needs.
Sumo Paint loaded quickly and did not hog my systems resources. I opened it from Firefox and was greatly pleased. I highly recommend this program for the entire family! Be sure to check it out!