Techniques for virtualized computer system environments running one or more virtual machines that obviate the extra host operating system (O/S) copying steps required for sending and receiving packets of data over a network connection, thus eliminating major performance problems in virtualized environment. Such techniques include methods for emulating network I/O hardware device acceleration-assist technology providing zero-copy I/O sending and receiving optimizations. Implementation of these techniques require a host O/S to perform actions including, but not limited to: checking of the address translations (ensuring availability and data residency in physical memory), checking whether the destination of a network packet is local (to another virtual machine within the computing system), or across an external network; and, if local, checking whether either the sending destination VM, receiving VM process, or both, supports emulated hardware accelerated-assist on the same physical system. This optimization, in particular, provides a further optimization in that the packet data checksumming operations may be omitted when sending packets between virtual machines in the same physical system.