I'm not really sure what I set into -cpuCount=(availableCPUcores) parameter seeing as I'm running a Sandy Bridge 2600k with 4 physical cores, and 4 "virtual" cores due HT, making it 8 "cores" total.
I usually always go the safe route and make it 4. Is there any extra performance gain if I were to go with 8? I tested with 4 and 8 in Benchmark, nothing really. But then again some people swear by it that they've gain a small performance increase.