Why is my <model-viewer> model loading so slow?

[lemonbanjosupply]

check out the model-viewer on this experimental website here: https://lemonbanjosupply.github.io/

check the out a couple of the options under "Which headstock shape do you prefer?" under "Headstock", as well as "What type of wood for your neck?" under "Neck and Fretboard" and "Neck Finish" under "Finish". Not all of these options are fully functional, but the ones that do work are the ones you can see the lag on.

Why is it lagging and/or loading so slow, but when it's on client only it's fine?