VMware regularly checks for unused virtual memory to return back to the host OS. This permits more concurrent virtual machines, but incurs a performance hit. Disable this by adding the line MemTrimRate=0 to the virtual machine's .VMX file.
You may want to avoid this overhead for guests for which host memory is plentiful and I/O latency is important. To disable page sharing, add the following line to the virtual machine configuration (.vmx) file:
# Disable logging - Only needed for troubleshoot.
logging = "FALSE"
Information taken from www.virtualization.info blog site and other websites.