Internet Service Provider (ISP) issues
Your internet speed ultimately depends on the service provider. Your ISP may change their network’s configuration or suffer technical difficulties that will inadvertently cause your Internet connection to run slower than normal. ISPs may also intentionally install filters or controls on the network that can lower your performance. Do not hesitate to contact your internet service provider if you suspect they are responsible for a slow Internet connection.
1. One of the best ways to test for network problems is to run a traceroute from your computer to the VPS. A traceroute will show all of the network hops between you and the VPS, including how long your connection takes to go through each one. It will also show network timeouts (with ***). In order to run the traceroute, enter the following command in your computer’s command prompt:
(See the Microsoft help page for more detailed information about this command http://support.microsoft.com/kb/162326 )
2. You can ask friends and contacts who live in a different city to try loading your website. If it is fast for them, but slow for you, you most likely have a network problem.
You should also test whether the slowness is limited to specific web pages, or if it is universal for all pages on the server. Many modern web pages contain dozens of complex elements that drag down the overall load time of the web page, and would do the same no matter how powerful or fast the host server is.
1. Your first speed test page should be a plain HTML document. You may already have a page like this on your server, such as an index.html page.
If the HTML page takes over 3 seconds to load, you may have a network problem or a web server problem. For network testing, see the previous section.
2. To identify which elements are slowing down your web page, you should use some additional diagnostic tools to break down your page load into individual items. Recommended tools: Firebug (Firefox and Chrome browser add-on).