Perhaps Internet Download Manager from Tonec is the fastest download manager I've found till now. When I first started using internet my only option is DAP. Because when I am new to internet, my only friend is google and what ever he says I followed it. When I searched for free download manager, Google showed DAP on top. So I went with it. In this way I came to know about download managers. Later I came know that there are many other download managers and all of them say that their download manager is the fastest and they also showed me some videos which will make an impression on viewers that their download manager is worth buying.
At this time I started testing the speeds of Download Managers. I personally tested DAP, Getright, IDM and Orbit downloader. I tested them on 2Mbps connection. These are the average speeds of them. DAP - 190 KBPS, Getright - 225 KBPS, IDM - 250 KBPS and Orbit - 218 KBPS (these speeds may not be actual speeds and they differ on the connection and its quality. So don't take these as references). From above it is clear that IDM topped them all. Also IDM has better features over DAP and Getright. IDM supports HTTP, FTP, HTTPS and MMS protocols where as DAP and Getright only support HTTP, FTP and HTTPS. In some regards Orbit download manager can be regarded as besrt. Though it is not the fastest but for sure it offers more features. For example, Orbit supports HTTP, HTTPS, FTP, MMS, RTSP and RTMP protocols.
Conclusion : If you wanna buy a download manager go for Internet Download Manager. If you want a free downlaod manager go with Orbit downloader.