Need to mention that its surely no memory leak since yours was at a steady 23%, so I kinda derped there(unless it was fluctuating?).
The 1mbs usage still looks fishy, but -broken record i know- did you try disabling your antivirus while updating? Sometimes active protections like to check every file, those too being downloaded and creating a bottleneck, and since you use AVG wich i despise(older versions were major performance hogs) I might give that a shot.
Other than that I have no ideas, best of luck to ya. Maybe it'll get around.
