Virtualized environments are important building blocks in consolidated data centers and cloud computing. Full virtualization (FV) allows unmodified guest OSes to run on virtualization-aware microprocessors. However, the significant overhead of device emulation in FV has caused high I/O overhead. Current implementations based on paravirtualization can only reduce such overhead partially. This paper describes the Linsock approach that applies the outsourcing method to speed up I/O in FV environments by combining different guest OS and host OS. Concretely, Linsock replaces the guest Windows’ network processing with the host Linux kernel’s on the same machine. Linsock has been implemented on Linux Kernel-based Virtual Machine (KVM) as the host virtual machine (VM) environment. Our measurement results with Linsock show significant performance increase of more than 300% compared with device paravirtualization in a 10Gbps Ethernet networking environment. In addition, Linsock also yields a fourfold increase in inter-VM communication performance.