A 60-watt incandescent puts out about 800 lumens of light. A 100-watt incandescent puts out about 1600 lumens. Your 10 60 watters put out about 8000 lumens total. It'll only take 5 100-watt bulbs to equal that. 60 * 10 = 600 watts heat. 100 * 5 = 500 watts heat. So, if the sockets can handle it, your room will be a little cooler if you switch to using 5 100-watt bulbs. The room will be just as bright. 150 watt bulbs, if you can find them, will give you still more lumens per watt.