So that option is actually there? Sounds likely to me that this is the issue them. Maybe windows gets confused because only the Minecraft Launcher is started with that option instead of the game itself? Does anything change if you select the option to keep the launcher open?
I found
this thread from 2010 that might work to enable the high performance mode for all graphical java programs.
Apparently you can usually also disable the onboard graphic of the cpu in the uefi/bios menu to force the laptop to use the dedicated card, but you probably don't want to do that because that optimus thing seems like a pretty good technology if it works.
Might still want to check if the laptop gets unusually hot, which could force it to slow down.