According to the rules, the max time for LRP is 10 seconds, but I've seen slow markets longer than that.
I have the same experience. IB likes to route their NYSE orders to Island for some unexplained reasons. As a result, I did not get the best fills on many NYSE stocks, costing me a lot of money. I have come to realize that IB is no better than other brokers. Their CNBC advertisment is totally misleading.