Sure, but nowhere do I see any indication that the airplanes are purposely being flown below their maximally efficient speed? Most of my flights are arriving early these days (I guess because of the padded schedules). They're certainly not lingering in the air any longer than they have to, because lingering in the air costs money that they don't want to unnecessarily burn.

As another commenter pointed out, even if the gate isn't ready yet, there's always room to wait somewhere on the taxiway (this has happened to me a few times recently). They'd rather wait on the ground with the engines idling than circling around in the air with the engines running at speed. Plus, it's not like gate availability is affected by schedule padding anyway; there's only so many gates at an airport, and they always are trying to turn over planes as fast as possible.