Some time the site takes too long to respond because the server response time in your configuration is low and the scripts doesn't gets enough time to load. To solve this problem, do as following steps mentions:
Step 1: Login to your cPanel account.
Step 2: Browse to MultiPHP INI Editor under the software section or simply search for "MultiPHP INI Editor" in the search bar.
Step 3: Then select the your desired domain/location and then edit the configuration files to increase your initial server response time.