It means that the geometry of your device has an increasingly bigger impact on your delay times. It's also going to cause more geometry features of your device

It means that the geometry of your device has an increasingly bigger impact on your delay times. It's also going to cause more geometry features of your device to behave like antennae, sapping power (and if you're the NSA, leaking information). This turns a digital logic problem into a digital logic problem AND a antenna design problem. This is part of the reason why we've been stuck at 3 ghz for so long. We can go faster, it just takes more power; something we've been moving away from.