I'm trying to update the code on a STM32F407 MCU using OTA and the update is sent through MQTT. The issue is that it takes a long time to update, I was wondering if there was a way to decrease the time. Also, if it's better to use MQTT or something else.

[Ozone]

Not much usable information.

The time is lost somewhere in the sequence chain of block reception, validity check, Flash programming, and response.

Check first where most time is spent.