This issue occurs because of changes in the architecture of certain CPUs. These changes affect the way that ESX Servers perform COW (Copy-on-Write) memory operations when using vSMP in a virtual machine.
There are two common ways to workaround this problem. Perform one of the following workarounds:
- Instead of rebooting the virtual machine, power-off and then power it back on. By doing this the problem is not noticed because the COW memory is cleared and repopulated upon startup of the virtual machine.
- Alternatively, you can disable pagesharing which resolves the slow performance. Pagesharing is used to reclaim duplicated memory pages across and within virtual machines. With pagesharing disabled we no longer share memory in this way, therefore the virtual machine consumes more physical memory because all memory pages are duplicated for each virtual machine running on the ESX host.
More info at vmware.com