Openvswitch is the most popular software implementation of an OpenFlow switch on the Linux system. Its current implementation includes a kernel module and a user space daemon. To connect with an OpenFlow controller and handle all the command message traffic, Openvswitch needs to transfer control messages between the user space and the kernel space of the Linux system frequently. When the amount of traffic becomes huge, control messages may be dropped in Openvswitch due to the lack of CPU cycles, causing performance bottlenecks. In this paper, we proposed a simple yet very effective design to improve the SDN control-plane performance of Openvswitch. The design is giving Openvswitch balanced chances to process the control messages in the netlink socket and the TCP socket so that the packets dropped in Openvswitch can be greatly reduced. Our results show that our optimized design can increase the control-plane message transfer throughput by up to 70% and make the per-second throughput very stable over time.