If it takes too long to load the EFI binaries, that might be BIOS setup issue. Have you tried other filesystems except FAT32 for the EFI partition? I’ve had luck with just FAT (FAT16) on some rigs that just refused to read FAT32 (still don’t know why).
Also, make sure the drives are in AHCI mode. Though this is mostly the default nowadays, I’ve seen weird BIOSes that defaulted to IDE mode.
The same applies for the other way around when I need Windows for something.
I apparently magically attract computers with a horribly slow UEFI so it takes a while to reboot regardless of the OS.
If it takes too long to load the EFI binaries, that might be BIOS setup issue. Have you tried other filesystems except FAT32 for the EFI partition? I’ve had luck with just FAT (FAT16) on some rigs that just refused to read FAT32 (still don’t know why).
Also, make sure the drives are in AHCI mode. Though this is mostly the default nowadays, I’ve seen weird BIOSes that defaulted to IDE mode.