annotation panel vertical scrolling is sluggish and labels move erratically

the annotation panel vertical scroll rate is set too low, so moving the panel up and down via mousewheel or by pressing up/down scroll arrows is slow for large numbers of annotation rows. The current redraw architecture in v2.7/v2.8 also means that the annotation label panel is redrawn independently, and so during scrolls, appears to move jerkily in response to scrolls, and goes out of alignment with the main annotation panel.