> With this change, the toolbar should no longer bust the image cache.
>
> Gregory, can you benchmark with this change (on an otherwise unchanged 
> trunk, i.e., with equal_lists, not !equal_lists)?
>
> diff --git a/lisp/tool-bar.el b/lisp/tool-bar.el
> index 8456216430..c3d0841d0c 100644
> --- a/lisp/tool-bar.el
> +++ b/lisp/tool-bar.el
> @@ -154,12 +154,12 @@ tool-bar--image-expression
>                                  (concat icon ".pbm")) colors))
> 	 (xbm-spec (append (list :type 'xbm :file
>                                  (concat icon ".xbm")) colors)))
> -    `(find-image (cond ((not (display-color-p))
> -			',(list pbm-spec xbm-spec xpm-lo-spec xpm-spec))
> -		       ((< (display-color-cells) 256)
> -			',(list xpm-lo-spec xpm-spec pbm-spec xbm-spec))
> -		       (t
> -			',(list xpm-spec pbm-spec xbm-spec))))))
> +    `(cond ((not (display-color-p))
> +	    ',(find-image (list pbm-spec xbm-spec xpm-lo-spec xpm-spec)))
> +	   ((< (display-color-cells) 256)
> +	    ',(find-image (list xpm-lo-spec xpm-spec pbm-spec xbm-spec)))
> +	   (t
> +	    ',(find-image (list xpm-spec pbm-spec xbm-spec))))))
>
> ;;;###autoload
> (defun tool-bar-local-item (icon def key map &rest props)
>

Hmmm... this fails with:

Loading /home/ghe/local/src/emacs/lisp/indent.el (source)...
Loading /home/ghe/local/src/emacs/lisp/emacs-lisp/cl-generic.el (source)...
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Eager macro-expansion failure: (void-variable image-load-path)
Symbol¢s value as variable is void: image-load-path