long duration gap when performance test

Hello everyone, I'm new in WebRTC. And I try to send and receive a 600KB image locally on my own computer via the DataChannel in a PeerConnection. I found that the end‑to‑end latency for the entire image transfer was 30ms. By adding logging, I observed that about 95% of the time is spent from the WebRTC application layer up to the point where the SCTP write loop is ready to write out this TSN packet. I'm not sure whether this is normal, because this speed does feel relatively slow.