Here are two options that are sure to speed up your drive access, though make sure you have a UPS if you enable advanced performance. Internal Drive
Right-click Computer, click properties, on the left click Device Manager.
Unfold the "Disk drives" tree (click the +), then right-click your drive, and go to the Policies tab at the top.
Under "Enable write caching on the disk" you will see "Enable advanced performance," tick the checkbox. External Drive
(Do not forcefully disconnect your external drive if you follow this, always use the "Safely Remove Hardware" option from Windows)
Follow the above steps, but this time (under the Policies tab) tick "Optimize for performance"
That should speed some things up.. I don't think that there are any power saving mechanisms that could render slow disk access, I could be wrong though
Also, I've found Explorer to be slow when the wrong type of folder is assumed. For example, my "Installers" folder on my external drive had the assumed folder type of "Music and video," it would try to load meta data from executables, making it a tad slower. Changing the folder type to All Documents sped things up a little bit, and eliminated useless columns.