Getting lots of hard drive thrashing in FSX while flying

I have 4GB of RAM, Superfetch turned off,and I was getting lots of hard drive thrashing while making my decent into LAX. I have MegaSceneryX SC installed. As I was closing in on the airport my frame rate was around 10 fps with lots of hard drive thrashing as I could hear my hard drive thrashing. Also it took longer for the textures to show on the wings while making my decent into LAX whereas when I took off from Las Vegas, the textures were loaded instantly on the wings when switching to right wing view. The plane I was flying was the Level-D 767-300. I have AI at 100% and use mainly WOA traffic and some that I put together manually. I don't have autogen turned on and ground shadows are turned off. I'm running the sim at 1600x900 with AA and AF turned on. Would upgrading to a RAID 0 increase my frame rate while the hard drive thrashing is going on?