One of the most important things you can do as a programmer to speed up a program aside from optimizing material removal rate is to reduce wasted time and motion within the machining process. Speeding up tool changes is an effective tool to reduce machining time. On vertical mills that move the table for X axis moves one method of reducing cycle time is changing the X home 2 position to a safe and optimal location. It makes no sense having your machine table rapid all the way to one side or the other when the part is in the middle of the table. Another way to reduce cycle time is to program G53 rapid moves instead of G52 moves to your safe tool change location. Always combine x, y and z moves where this can be achieved without causing a crash. Pre-staging tools is another effective way to reduce cycle time. Some machines even allow you to have the tool change door open and the tool pod down or ready before the spindle reaches the tool change location. Always consult your machines programming manual when looking for ways to reduce cycle time. Most machines have special G and M codes to help you reduce cycle time. Some even have parameter settings such as rapid tap and drill withdrawal.