Most of the time, the jerky swing meter is your system....
WGTadmin2:
Swing meter performance is tied directly to the local machine ram usage and cpu usage. It is true that you can have no connect to WGT's servers and still see swing meter stutter. If there is an internet connection or WGT server issue, this would manifest itself as a pause after you have already made your shot and the swing meter action has already completed. As mentioned above, a few thing WGT can optimize to assist in the swing meter performance is the decrease the memory and cpu usage on your local machine and correcting the invites is one of those steps. Thanks for caring - WGT
Please check the FAQs and the Video Turorials for optimizing your system. Clearing the cache will help the most.
Also, it is very important to learn how to NOT make contact with the ball if the meter is going to jump around. Just let the club swing through and it will look like you took a 'practice swing' with no penatly.
Hope this helps.