I'm not sure this is a Windows problem, but since it's happening on my Windows7 (Ultimate - AMD Athlon 2core x64) machine, I'm hoping an answer might be found here.
For over 3 years I've been transferring large folders (about 4GB) onto one of my four WD MyBook Essential 2TB USB external drives (only one is connected at a time). It usually takes 10 to 15 minutes to complete, but since last week it's been taking over an hour.
I tried it on the other MyBook drives and it was the same, so it's not the external drive.
I do not have the slowdown when transferring one of these folders to another internal hard drive.
Since this happened just after a Windows update, I attributed it to a glitch caused by one of the updates. I used system restore to back to before the updates, but that didn't help. I keep a periodically updated clone of C: handy in case of disaster, so I plugged that one in, booted on it, and the problems was gone - for one day. Then it was very slow again.
It looks like something is reverting my USB 2.0 system to working like 1.1 or worse.
Has anyone has any experience with this kind of problem? Any fixes or suggestions will be greatly appreciated.