Q:

What is the link between ssl ciphers I use (string length, strength of ciphers) and nginx performance?

All is in the question. 
I am wondering whether how using each ciphers or another would impact performance. Is there a huge impact ?
Is the impact linked to the type of content deserved ? (static or dynamic)
Thanks ! 

A:

The length of the key is really a reflection of the protocol used. The actual length of the secret provided is padded to a fixed length so generally, no the secret key length does not impact performance UNLESS it crosses over to a different protocol such as going from a 128 bit cypher to 256 bit.
At that point yes there is more CPU and other overhead that translates to performance... to work with keys of twice the size.

