iOS video lagging

I built the demo app and tested it between two iOS devices (iPad Air and iPad mini 2). Everything works fine, however the video quality is not so good, and there is at least a couple of seconds delay in the video streams. I'm not using any TURN server, and both devices are in the same WiFi network. The browser version works perfect and the video is much better than the iOS. My suspect is the VP8 codec is not performing well since there is no hardware acceleration in iOS.

Does anyone see the similar video quality issue? Is there a way to fine-tune the video settings?