Just wondered is the 5sec+ delay on reading my 1TiB external WD USB3.0 drive after a period of idleness?
Is this unique to SuperSpeed type USB or does all external USB drives have this delay before reading?
It is likely that the drive is going to sleep after a period of idleness. The delay is because the drive needs to spin up again before being read.
This is not specific to USB 3, many other USB drives do this.
I wouldn't worry (much). Check if there are any USB interface drivers that need updating, but don't lose any sleep over this, it's not the sign of some malfunction, probably just old drivers, or more likely, the following: the idleness does have a huge impact, because it's not a solid state drive, therefore has disks that need to spin for data to read. The disks stop spinning after a period of time, so that's another thing that you should factor in, that the disks need to start again after time.
Hope this helps!