To protect my website on a shared hosting plan, I added this to my .htaccess file:
<Limit GET HEAD POST> order deny,allow deny from .ru deny from .cn deny from .in deny from .de deny from .cz deny from .kp deny from .kr deny from .ng deny from .pk # other allows go here -- below is just a sample allow from 10.10.10. </Limit>
I ran like that for an entire year without issue. I also know that it worked because some guy from Germany said, "Hey, I heard about your website, but I can't connect to it." So, I got to trusting him and poked a hole through for him. He then said, "I can see your site. Thanks!" (The reason I block the above countries is two-fold -- one, they're not my target customers at all, and two, I was getting heavy spambot traffic from those countries.)
Within a week ago, however, the shared hosting plan server was upgraded to the latest CentOS and cPanel. Now all of a sudden I'm getting 13 to 15 second page loads. If I comment out the above block, then no slowdowns at all -- super fast page loads.
I tested from my Linux and Windows workstations at home testing with Opera, Safari, Chrome, Firefox, and IE. My neighbor, running Windows and Firefox, is on Frontier Communications DSL like me and she has the same latency.
My clients and the web hosting provider as well get instant page loads. It's only the connection with Frontier Communications DSL that's having the problem.
I replaced my DNS as a test. On Linux I can edit my /etc/resolv.conf and use Google DNS, and the web gets faster. However, again -- still latency to my website.
I know that if I call up Frontier, all they will say is they don't know why the problem is occurring and that the problem is the web hosting provider. When I called my web hosting provider (a2hosting.com), they told me that the problem was only with my ISP, Frontier Communications, and that I should call them.
What is the cause of this slowness only with Frontier Communications?