Two identical systems with different clock speeds, add-ons and number of monitors?

I know the quest for superb and fluid performance with a high-end system is akin to the quest for a Holy Grail.Personally I followed NickN's guide to the letter (and will likely reformat and NOT follow it, or follow it in part, for various reasons soon). One thing I did notice (and affected me) was that he essentially has you disable the Win7 Aero Theme. I seen in your screen shot, you appear to still have it enabled (window border).Go to System Properties -> Advanced System Settings -> Hardware Tab -> Performance -> Visual EffectsMake a note of exactly what you have checked right now, in order to go back after this test.Select the radio button "Adjust for best performance", then Apply. Reboot, see if that has any effect. It had a noticeable impact for me.If it doesn't help, change it back to what you had.Good Luck,

OK done a complete reinstall as per NickN guide to the letter and am now at 20 fps at Heathrow with settings at the start of the post. I am happy with that. Thankyou for all of your support, interestingly running 2 monitors made no difference at all to frame rates compared to using 1.Strange .......

A bit like tuning a car over and over again and still expecting it to drag a ten ton trailer up a hill :(

Love the car vs anything comparisons! Great one ;-)