Legacy Boot vs Standard Boot in Windows 10 (UEFI)

Question

In a device (UEFI) with two Windows 10 installations (one clear the other bitlocker encrypted) I noticed a difference in the boot sequence and boot time if the boot is changed from standard to legacy (using bcdedit).

With standard boot you have the new graphics and the boot sequence is as follow:
clear OS: start pc, bootmanager loads, OS selection, OS boots up
Bitlocker OS: start pc, bootmanager loads, OS selection, system reboots automatically, password screen, OS boots up

With legacy boot you have the old less fancy but effective graphics and the boot sequence is as follow:
clear OS: start pc, OS selection, OS boots up
Bitlocker OS: start pc, OS, selection, password screen, OS boots up

What I noticed is that with legacy boot in a UEFI system the boot sequence and time is much faster but I'd like to know from the experts what are actually the differences in standard vs legacy boot in windows 10? Is there any disadvantage in using the legacy boot, which appears to be faster and more effective, in a UEFI installation?

To clarify: it seems the question has not been understood, the BIOS is in UEFI mode and the two Windows installations were installed in UEFI mode and GPT. By using the command bcdedit you can change the boot in Windows 10 from standard to legacy, this setting doesn't change the BIOS which stays in UEFI mode! I'm just asking what are the pros and cons of switching to the legacy boot (the BIOS stays in UEFI!!!), from what I have seen apart from having the old graphics it is also faster...

Answer 1

Legacy boot doesn't support SecureBoot, which then effects other security features like HVCI.
UEFI boot has always booted faster than legacy boot from my testing. Boot speed also depends on boot media.
With UEFI boot, the boot splash screen can be changed in the firmware to replace the Windows splash screen on startup if you care for such a thing.

Answer 2

UEFI boot should be faster. UEFI is more secure, boot loader is protected. SPecially with additional secure boot you can then get all the secure features Defender family provides.

Answer 3

To clarify: it seems the question has not been understood, the BIOS is and stays in UEFI mode and the two Windows installations were installed in UEFI mode and GPT. By using the command bcdedit you can change the boot in Windows 10 from standard to legacy, this setting doesn't change the BIOS which stays in UEFI mode! I'm just asking what are the differences and the pros and cons of switching from standard boot to the legacy boot (the BIOS stays in UEFI!!!) in Windows 10. From what I have seen, the legacy boot apart from having the old graphics it is also faster...

Answer 4

@jelfer
Hi,
It would be to boot via legacy BIOS if you:

are actually setting up a virtual machine – UEFI on VM hypervisors tend to be limited and experimental; BIOS boot is much better supported
need to boot a 32-bit OS on a 64-bit machine
have a firmware known to be especially buggy
often swap or move hard drives between machines

Otherwise, it's better to go with UEFI. It's faster, more secure and comes with better functionality.

Some early UEFI firmwares may have the UEFI bootloader "bolted on" top of an otherwise BIOS-based firmware. In those rare cases, BIOS boot may actually be faster, but that's not representative of most hardware.

Hope above information can help you.

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Answer 5

The question is not clear.
The answers are clarifying BIOS settings.

Were / are you dual booting?

Are you attempting to distinguish between a graphical versus text-based bootloader? or boot menu policy?

These links may be useful:
https://appuals.com/how-to-enable-the-legacy-boot-menu-in-windows-10/
https://learn.microsoft.com/en-us/windows-hardware/drivers/devtest/bcdedit--set