Pretty Good Solitaire 12.0.1,keygen Why Does My Solitaire Move Jerky?

Why does my solitaire move jerky? - pretty good solitaire 12.0.1,keygen

My Mac OS10 old enough (maybe 6 years), but works very well for what I want. The only thing that really bothers me is when I play solitaire, moving the rate actually very easy to see the letters, the cursor will not "take" very good, and if it does not move smoothly. It's worse than a few days others.What this causes, and how can I solve this problem?