Server connect time significantly increased over the time I run my web site on D7 with enabled Cache pages for anonymous users option Cache blocksis off. It works pretty fast for non registered users but I started to observe significant difference for registered users (they can create content and do other things) over 2 months. Server connect time has grown. What can be a reason for that and how can I fix it?
You can use block cashing for users
you can check this link for more details https://www.drupal.org/node/326504
Check your MySQL server memory.