From what I understand, this information is displayed for pin-pointing where certain issues originate from.
For example, the Subreddit or these Forums might get a lot of reports about long matchmaking times, or laggy servers.
If they provide video's of the laggy servers, then they know the issue is happening, but if the SID (Server ID) is displayed, then they can internally look up the logs and see what might have potentially caused the issue. (Thus making it easier to resolve these issues)
The longer String of characters and numbers in the performance display is the SID, and so is the one in the Lobby. (Though the one in the lobby is a bit longer, I personally assume that this is likely a personal player identifier, though that's just conjecture)
In that case, it could be quite critical for them to resolve issues, as it could take longer without that.