When your system does not have enough RAM to perform an operation, Photoshop Elements uses scratch disks. A scratch disk is any drive or partition of a drive with free memory. By default, Photoshop Elements uses the hard drive on which the operating system is installed as its primary scratch disk.
You can change the primary scratch disk, or designate additional scratch disks. When the primary disk is full, additional scratch disks are used. Set your fastest hard disk as your primary scratch disk. Ensure that the disk has plenty of defragmented space available.
For more information on the subject please refer http://helpx.adobe.com/photoshop-elements/using/scratch-disks-plug-ins.html
Moving this discussion to the Photoshop Elements forum.