Slow draining glass vessel sinks

[BMBLBEE]

During a recent reno I installed granite counters in all the bathrooms and added glass vessel sinks I bought at Home Depot.

Unlike regular sinks these do not have an overflow and the drain fittng has a perferated disc to keep things from falling down the drain. When using the sinks water collects in the bowl and is slow to drain unless I swirl the water to release air bubbles just under the surface of the drain disc. It seems like air under the water is restricting the drain flow. Any suggestions for a fix that will let the water drain more quickly?

[Redwood]

Take a drill and make the holes as big as you can without trashing the grid strainer or, rip the drain out and install a lift and turn drain assembly.

The grid drains are noted for draining just like you describe.

[BMBLBEE]

Thanks, changing out the drain assembly was next on my list.