This my answer to another similar question in the Law section:~
As a retired Trading Standards(Food) Officer,may I add my tuppence here?
I have witnessed both Halal(Moselm) & Shechita (Jewish) Ritual Slaughter of animals.
I can assure you that,as razor sharp instrument is used,which severs the animals main neck arteries and nerves to the brain,the animal dies almost instantly(within seconds and NOT the time you seem to think).
Contrast this with the type of slaughter that you would prefer(and is indeed used for most slaughter of animals for non Moslem & Jewish meat eaters).
This merely stuns(but does not kill the animal) the animal is then gutted (whilst still able to feel pain) I have seen many animals slaughtered in all three ways,and see they way that they react to the disemboweling,and I know which way I would prefer if I were the animal.