Use a 6-quart slow cooker. Place the ham into the slow cooker insert. In a small bowl, whisk together the peanut butter, honey, soy sauce, garlic, and lime juice with a fork. Smear this thick sauce evenly over all sides of the meat. Lay a large piece of parchment paper over the top of the ham and push the sides down to cover it the best you can (this is to help trap steam close to the meat to keep it moist).

Cover and cook on low for 6 hours, or until heated through. Carefully remove the parchment paper. Let the ham sit for about 20 minutes before carving.