In Windows Server 2019, a new set of features is available from within IIS among some I mention here:
HTTP/2 provides for faster and safer Web browsing as result of new IIS hosting features. Originally, Serer 2016 added support for HTTP/2 in the native HTTP server. Windows Server 2019 delivers performance and security benefits to your web site deployments with HTTP/2. HTTP/2 is a rework of how HTTP semantics flow over TCP connections for Windows Server 2016. This is a major upgrade after nearly two decades of HTTP/1.1 use and reduces the impact of latency and connection load on web servers. The major advance of HTTP/1.1 was the use of persistent connections to service multiple requests in a row. In HTTP/2, a persistent connection can be used to service multiple simultaneous requests. In the process, HTTP/2 introduces several additional features that improve the efficiency of HTTP over the network.
Using HTTP/1.1 each request required a dedicated TCP connection potentially imposing several round trips to establish that connection. Using HTTP/2 further improves this process by allowing the ability to share a single TCP connection across many requests to the same web site called multiplexing.
From within IIS there is an option to Disable HTTP/2, do not do it!
HTTP exchanges typically employ many HTTP headers which many times represent much more data than the actual payload. HTTP/2 uses HPACK, a header compression scheme built explicitly for HTTP Header compression. This drastically reduces the amount of data that needs to be exchanged between client and server which may also save on round-trip times.