A couple of other simple tricks aginst stutters (although more constant and frequent-) I have read and perhaps worth trying, is turning FSUIPC's auto logging off and enabling Windows Aero-theme.
The last one seemed intuitive a little strange to me, as I had disabled it with both FSX and v2.5 and actuelly noticed some better performance and smoother simulation. But having enabled Aero now with v3, I actuelly noticed a smoother flow (not increase in fps), particular looking out of the windows down towards the ground flowing by.