We tried just yesterday to use Talk, but it failed miserably with only 5 participants and it does not support any other signaling server except the paid one from Nextcloud GmbH. IMO it is unusable in this setting if you are not willing to pay for the “high performance backend”.
Talk is based on Spreed.me (AFAIK) and spreed uses “WebRTC & libde265 H.265/HEVC”
I did set up a jitsi docker instead and we had a conference with a dozen participants audio only and one shared screen. Did perform well even on a very old dual quad core AMD Opteron 2350 Server. More than half of the participants had video enabled in the beginning and it wasn’t an issue.
As the server has a gigabit network connection I was only monitoring cpu load and did not watch the bandwidth usage.