1. A computer-implemented method for optimizing operation of a physical device in a virtualized computing environment, comprising: executing a hypervisor hosting a virtual machine; running an application, via a first execution thread, on an operating system of the virtual machine; issuing, by a device driver supported by the operating system and responsive to instructions from the application, control instructions to an emulated device, wherein the hypervisor and the device driver have a shared memory area, the control instructions issued from the device driver are written to the shared memory area, and the emulated device is an interface between the device driver and the physical device; monitoring, by a second execution thread of the virtual machine, the shared memory to detect data written by the device driver, the second execution thread to update a register value based on the written data to prevent a switch in control of a central processing unit (CPU) from the virtual machine to the hypervisor; reserving areas of the CPU's addressable space for I/O operations; and monitoring, by the physical device, the CPU's address bus and responding to the CPU's access of device-assigned address space.