Free memory

The Purge command lets you free memory used by the Undo command, the History panel, or the clipboard.

Choose Edit > Purge, and choose the item type or buffer you want to clear. If it is already empty, the item type or buffer is dimmed.

Note: The Purge command permanently clears from memory the operation stored by the command or buffer; Purge cannot be undone. For example, choosing Edit > Purge > Histories deletes all history states from the History panel. Use the Purge command when the amount of information in memory is so large that Photoshop performance is noticeably affected.