delayed dragging on screen using FS9

Hi:As this is video card related (I think) I thought it best to list here.I'm running FS9, PMDG 737 and FS Global 2005. Frames rates are set to 21 and I consistently get 21 frames with the exception of ariports where frames can reduce to 15.I find that when in 2D panel view and airborne, when rolling (changing direction of aircraft) the outside scenery seems to stutter and pause for a second before lurching to its nerw position. The lurch is only 1/2 a centimeter or so. It's not that annoying, but it never used to do this until recently. It only occurs on rolling as the scenery changes.I have played with settings and this does not alter the lurching screen.Any ideas??Thank you, Iain