STM32F446RE - RTC time drift under ''heavy'' load of wake up's and standby mode

Hey,

I am trying to test my MCU with the sequence bellow in order to check if i get time drift on the RTC clock.

loop on :

1. print RTC time + date

2.  enter stand by mode

I tested the wake up from stand by mode with :

1. ALARM every 5 seconds

2. rising edge on the WKUP pin

This sequence make's the RTC clock drift almost immediately and the drift is getting larger and larger as the time passes ( I print the RTC clock and compare it to a stop watch).

Am i doing some thing wrong that causes this issue ? I would be happy to supply any parts of the code if needed.

Thanks !