There are many and varied reasons why you could be getting a "jumpy" meter and many of us have spent time changing things about to cure this.
Let me add you NEVER get a 100% smooth meter, just too many variables to get that !!
Here is what I have done
Changed my browser to one that suits my system and WGT. I use this browser exclusively for WGT and NOTHING else. I use Maxthon, I as many others find this the best for WGT, but all systems are different and you may need to experiment a little.
Shut all other tabs and programs down when I am on WGT
After every game I reboot the browser
I run ccleaner through every day and sometimes more often.
There are other things I do, but try the above first, I'm sure it will help. I also have no doubt that others will offer other suggestions. My best advice is to try them and see what works.
Good Luck