Grub failling instalation on Old Macbook 4,1 (2008)

[Aravisian]

Your question reminds me of this option:

[HOW TO] Speed up boot using Systemd-boot

Some say that Gummiboot or Systemd-boot makes for a much faster boot time than Grub2 does. I have not tested this recently, but I can confirm it does work on Zorin OS 15 and on Zorin OS 16. Some users post on the forum looking for a way of speeding up boot time. Often, there is not a lot we can offer... aside from disabling a service here or there are recommending removing Snapd, which some users may prefer to not do. This is intended to be a linkable guide that such users may be directed to …

I have never tried this, so I cannot fully vouch for it.