Poorly done (or never done) computer maintenance of the player's computer is a known problem.
It may be that the computer at work gets routine maintenance by the IT guys that clears out temp internet files, clears the browser caches, clears the flash player caches, etc. computer. It is also possible the work computer has more free memory, fewer applications, a faster CPU, and runs cooler than your home computer.
If your home computer has a lot of applications and other stuff running in the background the meter won't be smooth. On your home computer close anything not needed to play WGT. Right before you play clear your browser caches and the Flash Player Website Privacy Settings panel and only open WGT's game client page - http://www.wgt.com/gameclient.aspx
With the WGT game client page open you should be able to right click on the screen and in the pop-up window click on Global Settings > Delete All > Delete Data to clear the Flash Player Privacy Settings.
A wireless mouse that has a weak battery in it can cause click lag. Many WGT players use a wired mouse for that reason.
Smooth meter - Optimizing your Windows computer