Please open a support ticket and provide this information so support can troubleshoot the problem for you:
1. Exact steps to reproduce the slow response including any login details or URLs to visit/browse.
2. Your IP address by visiting this page: www.myipaddress.com
3. Traceroute from your computer to the server. To do a traceroute on your windows xp computer, please follow this:
Start : Programs : Accessories : Command Prompt
Once there, enter this command:
tracert XX
where XX can be your domain hosted on the server or the server machine name (e.g. yodha.nocdirect.com)
Copy/paste the result in the support ticket.
4. Test result by placing a large file in your account and downloading it on your vps via http. For example upload a php source tar.gz from this page http://www.php.net/downloads.php to somewhere in your account via ftp, and then download it via your browser, and provide the download speed in the support ticket.
Note: If you have linux machine available, please try
wget http://url-to-php.tar.gz-file
And copy/paste the result in the support ticket.