And those examples are terrible.<p>This first example says "unstable" which is clearly false, so we can ignore him as ignorant.<p>The second two are both on windows, which until windows 7 was unable to schedule hyperthreading correctly.<p>The last example with linpack you are maxing out the core, so obviously hyperthreading won't help. Hyperthreading helps when you are not maxing out the core on any one task. Although a drop is not great, for regular desktop apps I think you'll have an overall net gain.<p>The OS task scheduler can switch tasks if one stalls for IO. A CPU based task scheduler can task switch on cache miss, or availability of single pieces of a CPU (like an adder).<p>Next he'll say not to run a multi tasking OS. Instead run each task on it's own CPU - "and don't worry we are making more CPUs soon".