I had a heavy spike in traffic today. So, had to move all of the IPv4 traffic to the server running Caddy (used to handle only 20% or so).
In the end, both the caddy server and the nginx server are dealing with roughly the same amount of traffic (20-25 Mbps each).
But Caddy seems to be running cooler than Nginx (which also has mod pagespeed in it though), consuming much less CPU. About 25-26% of the total traffic on Caddy is on UDP/443.
the top one is Nginx, and the bottom graph is Caddy. Both taken at the same time.