Why U-boot takes so long time in BSP 5.x - and boot time optimization

The platform I am working with is the following:

Apalis imx8qm V1.1B
Carrier Ixora 1.2A
Full HD 15.6’’ Ampire display (LVDS)
BSP 5.x

I doing some “performance test” comparing my new yocto system (based on BSP 5.x) and my old one (based on BSP 4.x).

Using grabserial to see the time of boot I noticed one thing:
In my old system the first line appears (the one which shows u-boot version) in 0.38xxx seconds, in the new system the same line appears in 0.88xxx seconds.
The versions of the u-boot are different but .config files are very similar so I can’t understand why the procedure takes such a long time on the system based on BSP 5.x