That's going to happen however you reduce the pipe. It's not the fitting, it's just the fact that you are reducing the pipe diameter. Depending on your pump, reducing from 1" to 3/4" may not be a problem. According to the manufacturer, 3/4" Loc-Line is rated for 1,140 GPH. If your pump output is well below that figure you should have little problem with stress or heat. If the pump output is close to or above that figure, you will need to find a different output or a smaller pump.