Nginx SSL花费太长时间

Question

为什么ssl需要这么长时间？没有ssl的请求时间在1s之内。

server {
        listen 80;

        listen 443 ssl http2;
         ssl on;
        ssl_certificate   cert/xxx.pem;
        ssl_certificate_key  cert/xxx.key;
        ssl_session_timeout 5m;
        ssl_prefer_server_ciphers on;
        ssl_ciphers ECDH+AESGCM:ECDH+AES256:ECDH+AES128:DH+3DES:!ADH:!AECDH:!MD5;

        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

}