So Adobe released Lightroom CC 2015.1.1 and new Wacom driver 6.3.13w3. In hopes of a remedy I thrashed Lightroom .plist preference files (keeping a backup) under my user account and did a fresh install of Wacom driver keeping nothing from previous version. Did that do any change? ... NO!
I'm getting seriously tired of this prolonged bug and it still affects; grabbing slider values and dragging (scrubbing ie. white balance), setting and dragging adjustment points on a RGB histogram, HSL picker tool and generally all sliders when scrubbing. As said before it needs a good push to activate any change, moving the pen fast and quite a bit of travel, then it jumps and moves alot. Thereafter it is somewhat smooth until you release the pen. Using mouse or tablet touch is as perfect as before, but I want to use the pen all the time. I belive that thelazydesigner is right about that this has something to do about Adobe programming a mouse slow down smoothing using LR to increase usability for accelerated mouses. But for pen and tablet usability this jerky and inresponsive feel is appalling.
Keep in mind after reading the forum thread that these issues only affect LR and not Camera Raw. Furthermore it is unaffected by turning on or off GPU acceleration. And sadly everything was working fine in LR 5.7.1.