My cornish x are not growing very fast. I have them on a high protein feed, but I think it's so hot they are not eating much. They pant horribly! I hose them down, but it doesn't help them much.
They were way too old when you butchered them. I think butchering at about 6-8 weeks old you will see a big difference. The older the bird, the tougher the meat.