Any command issued will consume CPU cycles but it's not just about reading the file, the order is on a basis I have stated prior.
The reason why I said for you to try disconnecting it is because WoW is a game of continuous "local streaming" meaning the files are always being accessed for whatever reason, it just has to find, process and load the file you need.
This gets inherently more active with a massive viewing distance so it's not just finding the file that causes CPU cycles affecting things.