Why Turning on HTTP/2 Was a Mistake
Shortly thereafter we noticed the servers behind our HTTP/2 load balancers had higher CPU load and slower response times than our other servers. Perhaps the most obvious solution is to have the load balancer throttle requests to the application servers, so the traffic patterns from the application servers’ point of view are similar to what it was using HTTP/1.1. Another (and perhaps better) option is to change the application so that it can handle traffic from a load balancer that accepts HTTP/2 traffic.
Source: www.lucidchart.com