Why does Windows Explorer take so long to display sometimes?

When you double click on My Computer it launches Windows Explorer which then goes off and constructs a summary of all the mass storage devices on your system, as well as a few other special categories of devices. ("Mass storage" devices, by the way, are disk drives and things that look like disk drives.)

Here's a look at mine:

As part of pulling together that summary, Windows Explorer actually goes out and queries each device listed for information. For example, in order to determine that my "C:" drive has 23.2 GB of space left, Windows Explorer actually checks a few things on the disk. Makes sense, right?

Similarly, in order to determine that drive "F:" is a "Removable Disk" (it's a USB thumbdrive) and that it's labeled "SPINRITE V6" (I have a copy of the excellent hard disk management tool SpinRite on it), it had to open and actually read the drive.

The most common cause of a delay in opening Windows Explorer is that one or more of the drives listed have become inaccessible.

For example, I have a persistent network connection on drive "N:" to a machine at my wife's business, but as shown in the image above, it's currently disconnected. Windows Explorer's attempts to get information about that drive will fail. That may add time - the failure may be in the form of a timeout. Windows Explorer will ask for the information and will wait for some amount of time for it to come back. When it doesn't, it labels the drive as "Disconnected" and moves on.

The timeout is typically noticeable, and if you have more than one network drive in this situation, it can be very noticeable.

The second most common reason for a delay is something called "spin up" time.

You can't tell from the display here, but my drive "E:" is an external Maxtor USB/Firewire hard disk that I use for backing up. Many disks, particularly external ones like this, will turn off their hard disks after some period of not being used to save power. The circuitry remains active, but the hard disk stops spinning. The next time that the drive is accessed for any reason, that hard disk must be turned on and must start spinning again. There's often a noticeable delay until the hard disk reaches its operating speed.

And yes, Windows Explorer's display can be affected by this delay.

The bottom line is that Windows Explorer is at the mercy of the devices it's listing. If any of those devices experience a delay in returning the information that Windows Explorer is asking for, you'll notice. Disconnecting network drives and perhaps unplugging other devices could at least give you a clue as to which device is contributing to the delay.