hi..just in time!
Same Problem Here, but..I notice that:

On Mac OS (I don't know if on WINDOWS too), the "PAN" tool is "realtime" responsive just if it sense the geometry stands below it on the viewport!

Otherwise, it took few seconds of lag time during the pan operation!

Infact, Just drag the drawings pressing the PAN tool in a blank area and voila'.. the lag is here!

Hoping for a workaround from the Apple's/Google's guys!

Regards (sorry for my ugly english)