Browser – SSL handshake
During connection establishment phase the browser also does SSL handshake in case of a secure connection. SSL handshake Root Cause can be caused by poor network conditions, slow client or server. Domain name is also used to group all requests affected by this given Root Cause.
As it is not always possible to improve network conditions then one can pay attention to server performance looking that it’s CPU is not under heavy load and there is sufficient RAM to keep previous connections alive. Also it’s good to not choose certificates with very long keys (RSA 2048 should be sufficient).