See if Mac OS X has enabled hyperthreading?
There is a way of disabling hyperthreading on Mac OS X: How to disable HyperThreading on Mac OS X Lion?
Is there a Terminal command of seeing whether Mac OS X has hyperthreading enabled?
Compare the result of:
$ sysctl hw.physicalcpu hw.logicalcpu
hw.physicalcpu: 4
hw.logicalcpu: 8
hw.logicalcpu > hw.physicalcpu so hyper threading is enabled