Parallel processing LBT on mac and w10

I’ve noticed that when running a ladybug shadow study on my iMac it is MUCH faster than when I run the same recipe on my windows 10 64bit 32 cores ryzen machine… the same simulation took 11 hours on the PC and just minutes on my iMac… Any thoughts on why this could be?

I have noticed that only one of the virtual cores out of the 64 available is active on the PC, even though the parallel-toggle on LB Incident Radiation component is set to On