Yes you can block instantly if you have high shield skill and are using fast shield. I guess you're using some big ass slow shield...
Only with 100 speed shields. They exist, but are in a minority. If a 2hander was whining about the speed of the 1handers, it would be the same for me to claim that you are wrong and all 2handers are faster than 1handers, even though it's just the bastard swords, the 2h mace, Longsword and the Katana. Yes, there are some shields who can block "instantly". No, most of them can NOT do that.