I don't know if this is an appropriate fix for this issue, i really think that the huge problem is the mass flood of commands that are being sent from the player to the server in which causes this lag. Myself i will hit my 1 key about 3-4 times and so forth and so on. How i have always played even while playing WoW. I believe if they would get rid of us having to constantly use abilities to kill mobs/players that it would alleviate some of the lag.
I have noticed many times when abilities go ON GCD when they shouldn't or the ability does not go off, my char will hesitate, or sometimes it bugs out so bad i can actually spam an ability that is not meant to be spammed..
This is an issue that really needs to be taken care of ASAP. It kills the game play when abilities do no go off when they are supposed to.