Hi James, there are a number of reasons why the swing meter may be jerky.
This is a good place to start for tips on optimizing game and swing meter performance: http://www.wgt.com/forums/t/635.aspx
Please check to see if your system exceeds our minimum requirements.
And don't forget to file bug reports! Right click from in the game and send us a report with as much detail as you can.
Thanks!