Something Seems Wrong....

Hi Guys - would be grateful for any help on this one....I feel like I should be getting more performance in fs9 from my system. At the moment I get between 15 and 30fps at say FSDreamteam JFK with 85% traffics and activesky. The strange thing is that the frames do not alter when I remove all traffic and clear weather??I know that 15-30fps is good already but it fluctuates around so much that it makes performance seem jerky and slow.I would loke to be able to lock frames at 25 and feel as though my system should be able to handle this with pretty much all sliders to the right. Grateful for any insight you have into this...Thanks! System specs below....Intel Core Due E8400 @ 3Ghz 1333FSB LGA 7752 x Kingston 1Gb DDR2 PC5300 memoryGIGABYTE motherboard 4 Core 1333-FULHD LGA775 ATI RS600 DDR2 Gigabit LANVista Home Premium SP1Nvidia