Slow connection start on busy server

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!


possibly time to increase the power of your server :wink:

With 40-50 seconds to complete the initial handshake this does sound rather long though.

What’s your domain name ? so we can look at it and test.

the strange thing ist that at the same time the http connections are fast as usual - connection times below 1 s.
You can use this URL:

If you use the server name without any page, it redirects on another server.

Thank you very much!


the most problematic time is between 09:00 and 11:00 MEZ.

The columns kmstatus1 and kmstatus2 are the time taken for the request - the first one takes long, the second is fast.
I have the same control running on another machine with http instead of https, and there the response times are always below 1-2 seconds.

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