If you do a lot of editing of a keyboard, and especially if you have been using the key unlinking features or creating dead keys, you may end up with some internal actions that are no longer used. There is no way to tell this just by looking at the keyboard layout, but it leaves a bit of extra information in the keyboard layout file, which may incur a slight performance penalty when the operating system loads the keyboard layout.

To remove any unused actions, simple choose “Remove Unused Actions” from the Keyboard menu. This command cannot be undone, so be sure to have saved your work before doing this.