This study focuses on the Internet of Things (IoT) gateway; a common middleware solution that bridges the gap between physical sensors and devices to internet applications. There is a shown interest in understanding the characteristics of different types of gateway architectures both from the research field and the industry, particularly the IT-consulting firm Attentec in Linköping, Sweden. A study has also been made on the open source C library libuv, used in the common web runtime engine NodeJS. The library has been used to study how asynchronous I/O operations can be used to improve the IoT gateway performance. A set of three general architectural approaches are identified. Common internal and external properties are identified based on state-of-the-art gateway implementations found in the industry. All of these properties are taken into account when a general gateway implementation is developed that is proposed to mimic any architectural level implementation of the gateway. A set of performance tests are conducted on the implementation to observe how different configurations of the gateway affect throughput and response time of data transmitted from simulated devices. The results show that the properties of the gateway do affect throughput and response time significantly and that libuv overall helps implement one of the best performing gateway configurations.