This much I agree with, subs take far too long to happen. A keeper should be subbed immediately, it shouldn't even need you to have an auto-sub selected - it's obvious who you would choose to replace. In the event of no GK sub, the player with best defence stats would automatically be put in place
Generally speaking, subs should take place within a few minutes. I've seen subs take more than 15 mins - and during that time many corners taking place. Duh! That's a break in play people, subs should happen then!