I have no problems of stutters etc running without this but after reading the bp=0 conclusions post I was excited about the fibre and the main scheduler thing hoping to get some boost. I decided to put it in use and as expected now I get main load on core1 with core0 varying upto 15-20%. I didnt find noticeable performance difference, maybe blurries taking bit longer to clear. using complex addon aircrafts, default scenery dx9 on win7 x64 with no background utilities running of any sort. Is this entry any good under default circumstances or am I better off without this?

What works for one does not work for all. Test on your system, with the aircraft you most fly, in the area you most fly, with the addons you normally use, with and without the affinity mask applied, look at your results and then you decide wether you need it or not. It can make a huge difference if you are running an addon that wants to use core 0 heavily...such as Air Hauler.

...I didnt find noticeable performance difference, maybe blurries taking bit longer to clear. using complex addon aircrafts, default scenery dx9 on win7 x64 with no background utilities running of any sort. Is this entry any good under default circumstances or am I better off without this?

I don't use the AffinityMask tweak. Doesn't improve performance on my system. There have been several investigations over time regarding this tweak. Some get better performance, some don't. Here is a general tuning guide by Nick Needham that's very good: http://www.simforums.com/forums/forum_posts.asp?TID=29041

It can make a huge difference if you are running an addon that wants to use core 0 heavily...such as Air Hauler.

but how to tell what kind of addons want core0 badly?

but how to tell what kind of addons want core0 badly?

You can run the Windows Task Manager (Ctrl-Alt-Del) concurrently with FSXand with FSX in windowed mode, you can watch the individual core utilizationsin real time.

but how to tell what kind of addons want core0 badly?

And after you have that figured out, why not run Ed Wilk's freeware SetAffinity II to take the application in question and have it run on a different core? I have everything else running on core3, and assign FSX to cores 0,1,2.Noel