Hmmm… this is on mobile? That’s brand new information.
These models didn’t seem very big for desktop but I suspect they are HUGE for mobile.
I have no experience with mobile so others will have to chime in.
…you definitely want to pregenerate light probes or use prebuilt ones, see: Texture of glb does not load - #14 by pspeed
That’s if you even use PBR on mobile. I don’t know what the recommended practice is these days.