Is it possible to know how much time grub takes to load files from /boot (vmlinuz and initrd) to the RAM?
As far as I know, the boot command loads and jumps into the kernel according to previous linux and initrd commands without any option to retrieve some stats about the processing.
Reading the source code of commands in grub's repo, I found testspeed which gives the load stats I wanted for a given file into memory:
grub> testspeed /vmlinuz
File size: 3.40MiB
Elapsed time: 1.571 s
Speed: 2.16MiB/s
grub> testspeed /initrd.img
File size: 48.80MiB
Elapsed time: 8.762 s
Speed: 5.57MiB/s