This isn't related to poor performance or lag. Second life has been functioning normally for me until today. Yesterday I updated to Second Life 1.20.16 (97603) and had no problems yesterday. Today I was using the control-8 control-9 and control-0 functions to zoom in on some things and shortly thereafter I noticed that whenever I am in first person view the camera jitters badly.
I have no idea what to do about this at all.