If you are having an issue with a slow MySQL connection to a remote database then perhaps the following can help.
Essentially my website was taking 7-8 seconds to load and the Apache logs weren’t giving me much to go on. Using a website page test tool such as http://www.webpagetest.org I could see that the site itself was performing well but there was a 7 second server wait time.
This lead my on to the assumption that the MySQL connection was causing the issue. To test, I simply created a new database locally and updated the config files. What do you know…the website loads instantly. This confirmed my assumption.
So I set about figuring out why the MySQL connection was so slow even though the remote server was within the same network. The fix is very simple:
Edit the hosts file on the remote MySQL server:
Add in the following line:
xxx.xxx.xxx.xxx original.host.com original
* xxx being the IP address
The original host being the server you are connecting from. Go back and check your website hopefully everything is back to full speed.
The main reason for adding the entry to the hosts file is due to not having reverse DNS set up. Once the entry has been added manually this will do the lookup manually rather than querying the DNS.
More useful information can be found here: http://etwiki.cpanel.net/twiki/bin/view/11_32/WHMDocs/SetupRemoteMySQL