c_move is based on c_trace with USE_BOX, thus c_trace without USE_BOX is faster than a c_move call.
c_trace is probably the most important Gamestudio function for all games, don't be afraid to use it. That means, use it whenever necessary and avoid it whenever possible. There are a lot of options to keep c_trace fast (use the IGNORE_... commands, keep the trace short, only use USE_BOX when necessary and so on).