OribitControls zoom-in loss fps

I create a demo. The link is claw machine.
I open it in phone. FPS is 60. I use oribitControls to control camera.When i zoom-in . It’s lost fps. FPS is 40.
Could you give me suggestions?I want to improve fps when i zoom-in.

phone has less power than pc, so the frame drops depend of the power of the phone. Is normal the device needs more power when zoom-in.

Something you can do I guess is reducing pixel ratio to 1, use cheap lights, textures and materia type.

NOTE: I test your claw machine in 2 phones and 1 pc

phone 1: 8fps
phone 2: 15fps
pc: 60fps

Thank you for your response. I change the code setPixelRatio(2).It’s fine in my phone.