Generally described, the present application relates to systems and methods for the managing virtual machines instances using a physical computing device and an offload device. The offload device can be a separate computing device that includes computing resources (e.g., processor and memory) separate from the computing resources of the physical computing device. The offload device can be connected to the physical computing device via a bus interface. The bus interface can be a high speed, high throughput, low latency interface such as a Peripheral Component Interconnect Express (PCIe) interface. The offload device can be used to offload virtualization and processing of virtual components from the physical computing device, thereby increasing the computing resources available to the virtual machine instances.