Correct way in new versions of nginx

Turn out my first answer to this question was correct at certain time, but it turned into another pitfall - to stay up to date please check Taxing rewrite pitfalls

I have been corrected by many SE users, so the credit goes to them, but more importantly, here is the correct code:

server {
       listen         80;
       server_name    my.domain.com;
       return         301 https://$server_name$request_uri;
}

server {
       listen         443 ssl;
       server_name    my.domain.com;
       # add Strict-Transport-Security to prevent man in the middle attacks
       add_header Strict-Transport-Security "max-age=31536000" always; 

       [....]
}

We have sometime a strange behavior with a server that is very cool ("uptime" will tell you) but becomes very irresponsive. One way to check is to use "netstat", see how many lines you have. You can try Apache mod_status too. Our problem is still not very clear but it certainly comes from the outside world, ie the datacenter connectivity. A machine near you could be eating all bandwidth, or even filtering the packets before they arrive to you, thus the perceived slowness.

Not sure if it applies to you, but you apparently have not a high load on CPUs while a lot of apache processes waiting for something, maybe they wait for answers from outside... If you have "sar" it can help too.