There might be some instances that your Internet is working properly, but still your browsing speed and downloading speed is very slow as compared to your normal average speed. This may happen because apart from your browser or download manager, various programs may be accessing the internet without your knowledge.
You can find out which other programs are accessing the internet with the help of software TCPEye. TCPEye is a freeware easy to use network monitoring application that will display a list of all the currently opened UDP and TCP/IP ports.
For the particular process that opened the port, all the information regarding that process is displayed, including the process name, full path of the process, version information of the process (product name, file description, and so on), the time that the process was created, and the user that created it, Country Name + Flag. Apart from this, TCPEye allows you to close unwanted TCP connections, kill the process that opened the ports, and save the TCP/UDP ports information to HTML, XML file, or to tab delimited text file and also get it checked for malware.
TCPEye also automatically mark with pink color suspicious TCP/UDP ports owned by unidentified applications. You can right click on any connection to view file properties, terminate the process that is using the connection or close the connection for that specific process. If you find a suspicious connection, you can even scan that process with the integrated VirusTotal Uploader to check if the process is a known malware, virus or Trojan.