Lag on One Client
For most people, you want all cores available and just to let Windows manage which thread is running where
I use dual hex core HP Z800s so I've 12 cores plus 12 hyper thread cores to play with. In the past I've found it best to assign cores to characters (minimum of 2 cores each) as that assures that no character is lagged out. Recently I've experienced problems similar to that of the title of this forum. Namely, one or more windows will lag out. And sadly my main, while not showing greater latency in the onscreen window, seems to fall behind the others in where they are in a fight. Main will show the boss mob at say 40 percent, and rest of raid will show the same mob at 20 percent. The health bar of the mob on my main will then flick back and forth between 20 and 40 etc.
So I have had a huge number of cores given to the main, as many as 12, THIS ACTUALLY SEEMS to make the problem worse. It seems as if doing this forces my computer to use all 12 cores even when less efficient and speedy to do so. The ideal might be to have a CPU strategy that says, in effect, you can have these 12 cores exclusively for my main but only use them as needed as opposed to you must use all 12 cores all of the time.
I've recently heeded the above quote and just assigned all 24 cores to every character and let windows 10 sort it out. BUT, I still find my main having the above issue...latency is same as others but he falls behind. I'm now playing with giving him more fps, it seems like with him at 80 fps and all others at 10 fps things are better. Now why this would be in cross-fired Sapphire Toxic R9 280xs is unknown to me but may have something to do at the rate at which information from in internet can be processed locally.