Verify that your IO devices are on the HCL http://www.vmware.com/pdf/vi35_io_guide.pdf specifically NICs and Storage controllers. If not get something from the HCL and disable the onboard devices. That will help quite a bit.
Edward L. Haletky
VMware Communities User Moderator
Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
SearchVMware Blog: http://itknowledgeexchange.techtarget.com/virtualization-pro/
As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization