Please have a look into the following example in android device.
It will work smoothly. Now try below example in the same device.
Now you will feel some lagging in the device. Try to open the navigation from the top. You can feel that lagging. What is the difference between these two. Why this difference in performance.
The transmission example has two spot lights in its scene whereas the GLTFLoader example has no lights at all. Besides, the blending computations of the transmission example require additional computing resources. The GLTFLoader example has not transparent materials at all.
This performance difference is visible on all devices, not only mobile phones.