First tries on Esp8266 with MQTT broker.
I was able to send and receive up to 1000 messages in few seconds before the heap run out.
Next to do is to optimize the memory usage, use a memory pool allocator, do some profiling to determin the optimum values for memory chunks....a lot of work to do.
Then do the
And a video with 1000 messages sent from and to my phone using ESP as broker. Don't forget that there are very small messages.