Ensure that hyperthreading is enabled for all ESX hosts. Hyperthreading, also known as symmetric multithreading, enables a single physical processor core to behave like two logical processors. Hyperthreading is enabled in the BIOS when an ESX host is booted.
Unlike having twice as many processor cores, which can roughly double performance, hyperthreading can provide anywhere from a slight to a significant increase in system performance. Tests indicate that Managers running on Linux VMs perform significantly better with hyperthreading enabled.
ESX provides configuration parameters for controlling the scheduling of VMs on hyper-threaded hosts. When choosing hyperthreading sharing choices, Any (default) is almost always preferred over None or Internal.