I’m having a similar problem.
My navigation is not great. I wouldn’t say unusable, but at best it’s stuttery with the pen. At worst, when panning, it gets laggier and laggier, until I let off the pen. And just like you it’s very smooth with the mouse.
Also the move tool seems to always give me a delay before it kicks in. It’s instantaneous with the mouse, but with the pen it almost feels like the harder I’m pushing down, the longer the delay is.
And I’m having a hell of time clicking OK when a dialogue pops up.
I’ve installed the wintab drivers. And I’ve disabled click and hold right-click.