I am limited to dual core at the moment so it wouldnt make a difference if I assign core utilization to applications, as FSX uses both when running after the SP1 update.
Thats not the point of my response, though, but can you set FSX to run on cores other than 0 or is it limited to the first 2 or 4 cores? In short are there limitations on what cores FSX can run on? I saw it mentioned that it has to use 0 for portions, but others will operate on 1,2,3 etc. Can FSX be directed to run only on 2 and 3 vs 0 and 1?
I know most programs are capable of running on any assigned core, with some exceptions as listed.
On a side note, if you are having performance issues with FSX, it could be a multitask lag. What I did on my old dual-core machine was have FSX set to a higher priority and it will get 'preferrential treatment' in the processor. This may cause other programs to have slow operation as you are forcing the processor to devote more power to FSX.
In short this will increase FSX performance but lower performance of other programs operating on the same core.
I am not as much in favor of prioritizing as I am with multi core utilization as it can impact multitasking, but you work with what you have.
On another side note, you can check your core operation in a 3d render environment, although not the only way to do so and usually not the most efficient, but it is effective to show if your cores are utilized. It will not tell you whats wrong if they are not, only show that it does or does not utilize. Most of them will default to CPU render than GPU render and programs like Blender, 3ds Max, Maya, DAZ, MAKEHUMAN( I think MH renders but cant recall), LuxRender, Yarafai, Kerkythea (or however you spell it), Truspace (limited based on setup), Wings3D, ZBrush, Sculptrix all will use multiple cores to render under CPU.
Might I recommend Blender. Get a blend file with a lot of nodes impacting the final render of a object. ensure blender is set to CPU render and render the scene. This will tell you if your cores are all working, as rendering can and will normally take a lot of the processors resources to compile the image/animation. It will sometimes staircase processors (step down the usage amount, using say 100% of 1 core, 95% of the 2nd, 50% 3rd, and a little on the 4th.)
GPU render will do in 10 seconds what takes CPU render 10 minutes. Unfortunately GPU is not available for most intergrated graphics cards (integrated graphics are pure evil in my view, portability and cost come at a price.)
You will need Task manager, Resource monitor or similar program to see the core utilization amount.