"Strange but unless I shut down my 2010 Imac at least twice a week scrolling gets sticky and jumpy.After I shut it down and turn back on its smooth as silk for about three days.Putting it in sleep mode doesnt help.It has to be shut down."
1. Try a quick log-out and then log back in. Any better?
2. Instead of a full shutdown, just restart. Any better?
Sometimes the simplest solution is the best. I suggest that you just restart the thing once a day. It takes only a minute and if you do so, you won't be bothered by the above problem.
I shut mine down every night, and then restart in the morning.
A fresh start for both of us...