Hi,
when my server gets busy, only https connections take long time, sometimes until the time out, sometimes more than 40 or 50 seconds. Http connections to the same server at the same time are really fast.
This is true only for the first connection, the second and all subsequent connections are fast again (if the first one does not time out).
My server is a Debian Jessie with Apache and PHP 5.
I have tried really a lot of different things, but nothing has helped.
My impression is that the certificate infrastructure is limited in some manner, i.e. has a maximum number of requests per certificate.
Before the Letsencrypt certificate, I had a EV certificate from Digicert, and that behaved worse. (I had the same behaviour as now with the Letsencrypt certificate 6 months ago, and when I changed the cerrificate, the server behaved much better, but the traffic is increasing, and now I have this strange issue also with the Letsencrypt certificate).
Thank you for any hint!
Wolfgang