Is CesiumJs support load 3d tile with KTX+gzip compressed texture?

Recently I want to reduce texture size both in disk and CPU/GPU memory, then I found gpu support some compressed texture format and Cesium support dxt/pvrtc/etc format too. I see a paper: WebGL Texture Compression Comparison – Cesium, it says KTX+gzip is comparable to the size of an image compressed to the JPEG format. Is CesiumJs support load 3d tile with KTX+gzip compressed texture and how? If anyone know, please reply in time, thank you!

Also I want to know:does real-time loading of KTX(+gzip or not) compressed texture affect performance and how much?

Waiting for someone to reply.