My experience with desktop hardware is that traditional BIOS boots faster than EFI, because the former does much less as well. (This is not the difference between "BIOS boot" and "EFI boot" options in an EFI BIOS, but rather a "pure native" BIOS vs "pure native" EFI with the same motherboard.)
Was that with or without a bootloader? My understanding was EFI was marginally faster to initialize (which might not be true based on what you're saying) but you could also skip the bootloader and load the kernel directly (EFISTUB) which would also eliminate initram (which seems fine assuming you're using vanilla VMs on popular hypervisors/providers)
