Unnecessary "v_streams" in JVB log

We are using Jitsi-meet API in a video conferencing application where we have people with different roles in the conference. While 2-3 people are with Audio/Video, rest 20-25 are audio only.
How can we optimise the server usage and reduce the number of v_streams in JVB logs?
We don’t want the “Audio only” participants to receive any of the video streams.

If participants are in audio-only mode they will not receive any video streams. Not sure whether we can switch that mode through the iframe API, though … something that needs to be added then.

If we set channelLastN=0 for those participants, will it be the same thing?

Yes, you got it right, but you will also want to add startWithVideoMuted=true if you want to not send video from that endpoint.