Remember, the only downside if your flight arrives on time and you clear immigration & customs quickly is that you'll have some extra wait time at the gate for your connecting flight. But (and it's a BIG BUT), if you have a very short connection time and you arrive at your connecting gate 2 minutes after the boarding process closes you've missed your flight. Error on the side of having a longer connection time rather than a shorter connection time. I travel often, have Global Entry and almost always get through Immigration, Customs & TSA very quickly but my rule of thumb is I never book an international connection with less than 90 minutes between flights. Two hours is better.