Let me first say that I am not very knowledgeable about the xlights code yet, only just started poking around in it.
But software must be written specifically to take advantage of multicore processors. And even when it is, having many cores compared to just a few doesn't necessarily make your software faster. Some work loads just don't lend themselves very well to running on many cores.
An example of a work load that benefits from multicore processor is a chess engine using a parallel search algorithm to traverse the game tree.
The reason I say that is because chess is a game of perfect information (ie you know the current state of the game at all times), so the work load can be easily distributed by all the available moves from the root node (ie current position). Since the order you search the moves from the root doesn't matter. They all have to be searched in order to find the best move.
However, you cannot use parallel processing to search the depth of the game tree and expect the same speed gains since you cannot easily predict what order you need to search the nodes in and the order of the nodes you search at depth is critical to the speed of the search (See alpha-beta pruning to understand why).
But one thing for sure, rarely if ever does multi-core processing result in a linear increase (ie 2 cores are twice as fast, 4 cores are 4x's faster).
So thinking logically about xlights, I don't think there are a lot of ways to improve it's performance using multicore processing techniques. Since I doubt xlights does much to tax the limits of a single core. Maybe background rendering performance could be improved a little, or doing a full render of a sequence could be improved since the order that the effects get rendered doesn't matter. But considering that there is a pretty big bottle neck that occurs during rendering since the rendering has to be saved to an fseq file (and secondary storage is pretty slow compared to the rest of the pc), you probably couldn't increase it by all that much.
So if xlights is programmed to take advantage of true multicore processing, it probably doesn't increase it's performance all that significantly. And certainly using a 10 core compared to a 4 core would probably add no tangible benefits. I can imagine few software packages that would benefit from a 10 core processor.
So I would pay special attention to the single core performance of a processor when you are building.
When you see 8 or more cores on a processor, it is usually more for power management reasons. So they are set up in a big/little configuration where half the cores are slow power efficient cores, and run when you aren't doing anything very demanding, but then when you do something really demanding the big powerful not so power efficient cores take over to complete your demanding task, then they turn control back to the little cores. Cell phones, tablets, and laptops benefit from this sort of arrangement.
Of course I am only talking about the consumer side of computing, business servers are a whole other type of beast where high core counts are mandatory since they are serving the needs of numerous users simultaneously, and it is easy to break down those work loads.
Hope this makes sense.
