CPU usage is determined by what the app decides to encode and decode. In VidyoConnect, we encode 720p30, and that combined with VidyoConnect's Chromium-based rendering causes it to use more CPU. We have plans to improve VidyoConnect's CPU usage in upcoming releases.
Vidyo.io is only a video chat engine with a limited GUI and hence, uses less CPU.
If more optimization is needed with Vidyo.io, application developers have the freedom to choose encode/decode, thus controlling how much CPU is consumed. Also, Vidyo.io uses the SDK’s native rendering pipeline, which is more CPU-efficient than that of VidyoConnect.