The putting grid uses an insane amount of CPU cycles, even for short putts.
If you're using IE, try a different browser like Firefox or Chrome.
Scan your computer for spyware/malware as those items can create unneeded CPU activity along with unneeded tcp/ip connections.
Open Task Manager and monitor it while playing. When the CPU usage spikes to over 50%, do not attempt to swing. Only swing the club when CPU usage is below 50%, otherwise the swing meter will stutter (and sometimes even freeze).