When I upgraded from WiFi to a physical CAT5E cable running between my router in the other room and this desktop, I jumped from 2-3MB/s tops (1MB/s usually, sometimes less) to 11-12MB/s speeds during file transfers from my home server.

Lately I was checking that the speed to download some fansubs off the server got down to 5-6MB/s, exactly half of what I was used to; I noticed there was another non specified adapter listed in Windows 7’s statusbar icon hover, and I traced it to Virtualbox’s bridged network adapter. Since I recently had installed that to test something for which I had no need anymore, I simply uninstalled Virtualbox, and as soon as the virtual network card driver was gone, speeds were back to 11-12MB/s.

Should this be in any way a normal behaviour?