Different boot times for dual Windows 11 installations on same PC

Hi folks. I've successfully installed and isolated two installations of Windows 11 on my PC. One for work (Pro) and one for games (Home). I've moved the EFI partition to its own dedicated drive and removed the original and things work flawlessly. I've disabled Fast Startup, and disabled the drive for the alternate OS in Device Manager and they appear to be completely isolated from one another. The strange thing is that when selecting which OS to start on the bootloader, the original (work) installation starts up very quickly whereas the second (games) installation restarts the PC and takes much longer to load.

I can't understand why because the EFI/bootloader partition is completely isolated on its own drive and both OS installations are on fast M.2 NVMe SSDs so I can't account for the difference. I've double-checked that Fast Startup is disabled on each, there is no hibernate file and neither are encrypted or have any substantial difference in configuration.

Could anybody provide any insight into this? I'd appreciate it.

Thanks.

Mine is the same, the last Os installed will be the default OS unless you have specified a different OS after installation and this will preload ready for deployment, that's why when you select the default it loads very quickly, when you select another OS it goes through the initial boot process all over again so takes a little longer. Hope that makes sense, I'm sure someone will be along with over complicated technical jargon to explain the same thing but in essence that's how mine behaves.

You

Thank you very much for your answer. That actually strikes me as a bizarre decision given that I always assumed that the bootloader would be an independent component of the boot process and that having it interact with the OS (or multiple OSs) would violate the ideas of compartmentalisation and least privilege. I can understand some interaction such as facilitating a chain of trust but preloading the OS takes me by surprise.

CornishRattler said:

Mine is the same, the last Os installed will be the default OS unless you have specified a different OS after installation and this will preload ready for deployment, that's why when you select the default it loads very quickly, when you select another OS it goes through the initial boot using msconfigprocess all over again so takes a little longer. Hope that makes sense, I'm sure someone will be along with over complicated technical jargon to explain the same thing but in essence that's how mine behaves.

You

Click to expand...

Yeah, I get similar.

I just did a test by changing the default OS using MSConfig to one I wanted to boot into, and it booted much more quickly.

I never really thought about this, but now you have pointed this out, I may produce a batch file using

bcdedit /default {88240e47-5ebf-11e7-98a8-b123c369fcff}

where figures in {} are the guid for os I want to boot to.

I would a series of these for each guid, and a simple menu to select whichever I wanted.

Then I would have a shutdown and restart command.

Small project for weekend.

cereberus said:

Yeah, I get similar.

I just did a test by changing the default OS using MSConfig to one I wanted to boot into, and it booted much more quickly.

I never really thought about this, but now you have pointed this out, I may produce a batch file using

bcdedit /default {88240e47-5ebf-11e7-98a8-b123c369fcff}

where figures in {} are the guid for os I want to boot to.

I would a series of these for each guid, and a simple menu to select whichever I wanted.

Then I would have a shutdown and restart command.

Small project for weekend.

Click to expand...

Whichever one you have as the default OS will boot quickly, the other(s) will take longer after selecting at the boot screen. We are only talking seconds here mind
I have W11 Beta as my default. W11 Dev and W10 take longer to boot, if I change the default to W11 Dev then W11 Beta takes a little longer etc, etc

CornishRattler said:

Whichever one you have as the default OS will boot quickly, the other(s) will take longer after selecting at the boot screen. We are only talking seconds here mind
I have W11 Beta as my default. W11 Dev and W10 take longer to boot, if I change the default to W11 Dev then W11 Beta takes a little longer etc, etc

Click to expand...

You say seconds, but it is 12 seconds difference on my pc, and that is with fast nvmes - it is restarting twice in effect that slows things down. Batch file will take 1 second.

cereberus said:

You say seconds, but it is 12 seconds difference on my pc, and that is with fast nvmes - it is restarting twice in effect that slows things down. Batch file will take 1 second.

Click to expand...

So in essence you're changing and pre-selecting the default OS before you shutdown, I think it's about 10 seconds on mine but 10 or 12 it's "seconds" all the same. Just thinking of what else that's productive (apart from switching the kettle on) I could be doing in those fleeting moments and I'm not coming up with much tbh