Several IoT middleware protocols have been proposed for the wireless IoT data transfer. The main representatives are the Constrained Application Protocol(CoAP), the Simple Object Access Protocol (SOAP), the message queuing Telemetry Transport (MQTT) and the HypertextTransfer Protocol (HTTP). Protocols deployment constraints are the message delay, message loss, processing effort and power consumption that IoT devices demand, in order to successfully transfer wireless data. In exchange for the reduction of device energy consumption, many of these IoT protocols try to lower the data throughput, minimize security, or even limit coverage. In this paper authors compare the performance of IoT application protocols using Machine to Machine (M2M) delay scenarios measuring the extra effort that they enforce to the transmitted data. Experimentation results reveal which protocol is best suited for different network and application scenarios accordingly.