This paper is a guide for selecting an IoT embedded platform depending on the required performance, in streaming scenarios: data is received via UART, is processed (e.g. IAXPY, GEMM, AES encryption) and then is sent back via the same data interface. Platforms: 8-bit AVR (ATMEGA328P of Arduino UNO), 16-bit TI (MSP430), 32-bit RP2040 (Pi Pico board), 32-bit LX6 (ESP8266 and ESP32), 32-bit TI (CC3200), 32-bit STM32.