In order to get the most out of your Virtual Infrastructure you should consider enabling Jumbo Frames in your network. Jumbo Frames simplified is ethernet frames that can carry up to 9,000 bytes of payload. VMware added support for Jumbo Frames with ESX 3.5, Build 64607 (ESX 4.0 supports Jumbo Frames as well):

Build 64607 Release Note:
* Enhanced VMXNET—Enhanced VMXNET is the next version of VMware's paravirtualized virtual networking device for guest operating systems. Enhanced VMXNET includes several new networking I/O performance improvements including support for TCP Segmentation Offload (TSO) and<strong> jumbo frames</strong>.

Below are the steps needed to get Jumbo Frames online in your network:
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1. Ensure that your switch supports Jumbo Frames and that it is turned on (at this point you should all set, but it is definitely worth double checking)
2. Log in via the VI client or vSphere client and select the vSwitch in question (in this case vSwitch2), edit the properties and set the MTU to 9000 (click OK)
3. Putty into your ESX host and double check the currently vSwitch config by typing: esxcfg-vswitch -l (you should see output under the MTU column referencing 1500)
4. Input this command to change the 1500 to 9000 by typing: esxcfg-vswitch -m 9000 vSwitch2
5. Double check the command is in place by typing: esxcfg-vswitch -l (and this time around you should see the MTU column referencing 9000 aka Jumbo Frames)

Again this is something that you proceed carefully through as enabling this on in your VM environment with a switch that does not support Jumbo Frames will result in dropped packets, but if you on the right side of the hardware equation you'll be glad you did. Reducing the load on the CPU by requiring fewer headers and overhead to be processed is a good thing.