Process distribution, communication and deployment

Thank you Chris, yeah I know that, but I was wondering: when a node connects to the entire cluster, that node actually has n-1 connection to the other nodes. So let’s say in a cluster of 3000 nodes each node maintains 2999 connections. Keeping just the connections alive should be such a problem but for performing heartbeat can use some resource. What’s not clear to me is how this can impact the performance on that host? In theory heartbeat should be done with very small messages that are not been sent every microsecond right?
So if that’s the case, what’s the underlying reason why performance degrades?