If your Hard Drive kicks in now and again (observe the light) whilst flying, spooling scenery data for the Sim and slowing everything down, then you do not have enough RAM installed...

...!
Once I have started the Sim, my Hard Drive has no further use, all my data is stored in my fast RAM.
Paul...Win XP...FS 9....2.3 GB... 8-)...!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.