Hi kiwi trader.
Well if you're speed-sensitive, as many other option traders are, you should trade thru the brokerage firms with sufficient line capacity. Line capacity meaning how many option order lines they have between broker's end and the KRX (the exchange) First of all, If your broker doesn't have a full "clearing" membership with the exchange, they are not supposed to have their own lines. There are many big-name firms that operate in Korea without the full membership and clear their clients trades thru their partner firm with the full membership. I'm sure you'd know what this means. Bottleneck problem. Every click you make, you're one-step behind. Related information is shown on the KRX-website but I don't mean to hurt their reputation because they could be good in other field of services than on the speed side so I'm not mentioning their names here.
Even among the brokers with the full membership, the KRX has made it their policy to allocate different number of lines to each one of them according to their trade volume. The bigger they are, the more lines they have. So my bottom-line here is "stick with the top one or two big guys and never look at small guys tempted by the cheap commissions and stuff.
Sorry I gotta run now. I'll get back to this thread later