"The application note states that everytime you use a local variable, a copy of variable is made. Can someone explain to me why this is?"
LabVIEW has to ensure that everything is reading and writing from one master copy, so simultaneous reads and writes do not collide. "Also, if I am writing to an indicator in many different places in a VI diagram, then it is convienent to use local variables...is it possible to use the indicator directly in multiple places (meaning that the indicator shows up on the diagram multiple times)?" A Case Structure or a Select Node, e.g., can let you choose dynamically between multiple outputs. And if you have a loop around the control/indicator, it will be read from/written to once for each iteration of the loop. Also, local variables are more than a performance problem; They do not follow data flow. This makes it a real problem when debugging because the execution order is more complicated and less deterministic.
