samples like dragon by Khronos (https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/2.0/DragonAttenuation/screenshot/screenshot_large.png) use
KHR_materials_transmission, KHR_materials_volume, KHR_materials_variants extensions.
Everything is working really nice on desktop, although on mobile (e.g. smartphone) refraction indeed has huge impact on fps.
Is there a way to disable specific KHR_* extensions in THREE?
In that case, one could disable certain extensions on low-profile devices