Which configurations can ensure video and audio at a good enough quality with audio being clear and video not dropping frames (even if the video is a bit blurry, that’s fine)?

You can lower the video quality in the bottom right menu. You can even limit your own camera's capture resolution, for example #config.constraints.video.height.max=360 . See https://github.com/jitsi/jitsi-meet/blob/master/config.js for all the options.