Nginx – Why is $request_time sometimes much bigger than $upstream_response_time

It doesn't work that way: the SSL handshake happens before HTTP, so the name on the certificate will get evaluated in the browser before you can redirect or do anything else inside the nginx configuration.

I liked the quest very much, and I analyzed it.

I took these resources mostly: [https://www.nginx.com/blog/nginx-1-9-5/ ] [https://www.nginx.com/blog/http2-module-nginx/ ] [https://blog.cloudflare.com/introducing-http2/ ] [https://http2.github.io/faq/ ] and this PDF

You probable downloaded nginx/1.9.10 from Nginx.org http://nginx.org/en/download.html. Please confirm. Have you built it from source? Have you tried the nginx/1.9.12?

As you may see in CloudFlare article when measured Average Page Load time HTTP/2 is clearly the winner (at least for their web site).

Access via HTTP Protocol Version    Average Page Load time
HTTP 1.x                            9.07 sec.
SPDY/3.1                            7.06 sec.
HTTP/2                              4.27 sec. 

However, when tracking average response time, please check out the second article from Nginx.org I set as a reference where it reads:

The next key point of HTTP/2 is multiplexing. Instead of sending and receiving responses and requests as separate streams of data over multiple connections, HTTP/2 multiplexes them over one stream of bytes or one stream of data. It slices data for different requests and for different responses, and each slice has its own identification and its size field, which is there so the endpoint can determine which data belongs to which request.

The disadvantage here is that since each chunk of data has its own identification, its own fields, there's some metadata that transfers in addition to the actual data. So, it has some overhead.

The other problems may be related to your nginx setup, for instance inside the server block.