Modern Intel processors sometimes have a split between P and E Cores (Performance and Efficiency.) For example, you’ll see Intel Core i9 processors with 16 cores (8P + 8E). These Efficiency cores are advertised as handling background tasks more efficiently.
Is anyone aware of any conflicts or issues with these cores when it comes to rendering or simulations in Blender? Should I be looking to get a processor with all regular cores?
I have not heard of major Blender bugs with Alder Lake and Raptor Lake, but keep in mind that you will need to have Windows 11 as your OS if you want to make the best use of it (that is unless it becomes the time you switch to Linux).
Ah yes, I was aware of that.
I suppose the next question is if there are any issues with Blender and Windows 11 
I’m not aware of any performance benchmarks where Windows 11 performs better than Windows 10 in Blender. I’m using Windows 10, with no plans of moving to Windows 11, and my OpenData benchmarks are slightly higher than the average for both CPU and GPU