Swing meter stutter on PC?
It runs without connection to WGT, so that's a local phenomenon, everything that occupies the CPU: CPU and memory load, drive load, WLAN & LAN load...
A regular culprit is Flash, blocking memory over time. Thus, the first measure is to close all(!) browser windows to clear that, and re-open (also possible during solo play).
Next, stop downloads and music and other unnecessary programs and processes on your PC and observe if another client uses your LAN+WLAN.
Some browsers work better than others - try them out!