First off, if you go looking for Hyperthreading settings on the Legion Go, you probably won't find them, that is because Hyperthreading is Intel's brand name for the actual architecture called SMT (Simultaneous multithreading)
To change this on the Legion Go, you will need the latest bios which is currently in Beta and should be released soon, if you want to install the latest bios you will need to download it directly on the Legion Go from here and you can follow our video guide on how to install that as well as change VRAM below:
The SMT setting is in the bios in the same place to change the VRAM settings.
To enter the bios, first turn off the Legion Go completely by shutting it down from the power menu.
To enter the bios menu, you need to hold the Volume Up button + Power Button until it turns on, keep the volume up button pressed but let go of the power button when it starts up until you see the following menu:
Select bios setup and you should enter the bios menu
Select configuration and you will see the options to change the UMA Frame buffer (VRAM) and you can change this to what you feel is best, 6G gives the best balance overall but some games require more or less depending on the amount of Physical RAM they need.
Scroll all the way to the bottom and you will see the SMT option
Change the setting to disabled
Then tap exit on the top left, select exit saving changes and say ok on the dialog to save the changes and reboot the Legion Go
That's it, you have now disabled SMT (aka Hyperthreading) for your Legion Go.
We are testing out the difference this makes for game performance and will have a video available soon with the results. Let us know in the comments if this made a difference for any of the games you tried.