Windows boot loader tripleboot across 2 disks - speed?

Here's the scenario:

A win10 laptop with the OS on an SSD and a 1TB storage drive. Starts/boots fast, no problems.

1) I partition The storage drive and cut out 2 separate 80GB partitions to also boot Linux and win8.1.

2) I install Linux mint cinnamon on one of the partitions. Leave it so I have to jump into the bios if I want to boot into it. It boots fast from the bios and otherwise win 10 boots fast from startup as before.

3) I install win8.1 on the other partition. It's super slow to startup and boot. It installed a blue boot screen that lets me pick between win8.1 and win10 at startup. I fear that it's sooo slow because it's accessing both drives while trying to give me the boot option.

4) So the question: is there a way to use separate boot loaders, or force win8.1 to not attempt to be accessed on startup without going through the bios?

This will use win10 90% of the time but I want the other systems on there in case I want or need them, but I don't want them to even be looked at unless I tell the bios to.

Thank you.

Using the Windows 10 bootloader on the SSD, and GRUB on the HDD should do what you're expecting. Leave the Win10 boot config untouched, and manually select the HDD with your boot menu key if you want to boot to 8.1 or Linux. Virtual Machines may be a solution for all or part of what you're trying to do.

If you want to prevent W8.1 from trying to start you can boot into W10, go to System Configuration, than Boot Settings and than select W10 as the default OS to boot from. If you want to go with the VM route (wich I prefer to dual boot), as @kewiha said, using VMWare Workstation Player 12 gives you the possibility to use the W8.1 machine integrated with the host system with an option called continuity. You open programs and access windows as W8.1 and W10 were one OS.

Thanks to both of you, unfortunately I won't be able to test it until I get it back in my hands at the end of the week.

I didn't realize you could access boot options from within the OS in the system configuration menu, I just kept trying through the bios - I'll give it a shot.

Unfortunately for this application I can't us a VM, 8.1 needs to be a straight install with minimal overhead.