LeonDelBosque:
if it's true that friends' activities affect your play, closing the original WGT window and keeping only the game window open should eliminate any related meter hiccups. this way you don't have to alienate your friends :)
Unfortunately, closing out the original WGT window (aka 'Profile' window) does not stop the play window itself from registering each change of status of any of your WGT friends.
The more friends you have, and the more active they are, the more likely it is that a status change will occur in the midst of your downswing ... thus injecting a signal which can impact meter smoothness.
It has been reliably reported in related threads that the top WGT players zero out all their friends prior to participating in the virtual Opens. After reading that I reduced my accumulated WGT friends by 90+% - to only those in my club - and noted a dramatic reduction in meter glitches. It won't totally solve the problem, sadly, as there are many potential 'noise' sources on most people's computers.
As noted elsewhere, having a clean browser (I use Comodo Dragon) and using GameBooster also help game stability.