nice but....

NO no no no no Shirley (in a Dr Cox-like voice)

#IfWinActive, World of Warcraft
~1::
ControlSend,,{1 down}{1 up}, ahk_id %wowid1%
ControlSend,,{1 down}{1 up}, ahk_id %wowid2%
ControlSend,,{1 down}{1 up}, ahk_id %wowid3%
ControlSend,,{1 down}{1 up}, ahk_id %wowid4%
ControlSend,,{1 down}{1 up}, ahk_id %wowid5%
return
you only need one [code:1]#IfWinActive, World of Warcraft[/code:1] as all hotkeys below that line are governed by that instruction. I don't know about the internal working of AHK but it is possible that each # instruction is independent in memory and so this could lead to inefficiency

also don't use ~ , this passes through the native keypress to the active window as well as sending that keystroke to each of the wow instances.

a better solution would be
[code:1]1::
ControlSend,,{1 down}{1 up}, ahk_id %wowid1%
ControlSend,,{1 down}{1 up}, ahk_id %wowid2%
ControlSend,,{1 down}{1 up}, ahk_id %wowid3%
ControlSend,,{1 down}{1 up}, ahk_id %wowid4%
ControlSend,,{1 down}{1 up}, ahk_id %wowid5%
return[/code:1]