Originally Posted by
Nyalia
Macros cannot know your GCD. They cannot know your skill cooldowns. The macro will literally wait the time specified, and then try to execute the action. If the action is off cooldown, nothing will happen, but after the next delay specified, the next command will be attempted. In other words, macros do not "queue" moves.
If you are using skills manually and you hit a skill that has 0.5 seconds or less remaining on the cooldown, the skill will flash and then the second it finishes cooling down, it goes off. This is called "queuing" a move, and it not only eliminates any delay due to user input, it also eliminates any delay due to latency because the queuing happens on the server. If you use a macro, it can't queue because the game has no idea what skills are being used in the macro since you can have several or none. So, even if you have a single skill macroed (something like /ac "Spinning Edge" <t>, /p "Ha! Take that, evildoer!"), if you hit that macro when a skill is 0.1 seconds from cooling down, it won't do anything. Because of this, macroing GCD skills at all is a major DPS loss.