Investor William Ackman is turning up the heat on the man he handpicked to turn around J.C. Penney. The “criticism is deserved,” Ackman said of CEO Ron Johnson. The retailer’s stock has plummeted 27.6 percent in the first quarter. During a conference in Boston, Ackman, who sits on Penney’s board, said there was “too much change too quickly without adequate testing.” He said Johnson faces a tough challenge in fixing the company. Still, Ackman said that the retailing business can be very lucrative if done right.