Question about STARTUP_SLEEP_DELAY_DEFAULT and first boot time

Hi,
I want to make my device to boot fast on first boot, but it still takes more than second. I'm using secondary bootloader (with AES encryption) in the OTP and SPI flash memory.
The problem is that the device must start and run on very small coin battery (CR1025). I found this constant (STARTUP_SLEEP_DELAY_DEFAULT) in arch.h.
What will happen, if I lower its value?