diff --git a/ui/bookmarks.js b/ui/bookmarks.js
index 19fb995f..4e63717b 100755
--- a/ui/bookmarks.js
+++ b/ui/bookmarks.js
@@ -147,7 +147,7 @@ function setupBookmarks(viewer){
 
 	return viewer
 		.on('sortedImages', function(){
-			BOOKMARKS.sort(imageOrderCmp)
+			BOOKMARKS = fastSortGIDsByOrder(BOOKMARKS)
 		})
 }
 SETUP_BINDINGS.push(setupBookmarks)
diff --git a/ui/data.js b/ui/data.js
index f246c0a2..723d1841 100755
--- a/ui/data.js
+++ b/ui/data.js
@@ -536,6 +536,54 @@ Array.prototype.binSearch = function(target, cmp, get){
 */
 
 
+// This is a cheating fast sort...
+//
+// By cheating we might use more memory -- this is both not in-place 
+// and may use quite a bit of memory...
+//
+// The gain is that this is SIGNIFICANTLY faster than using 
+// .sort(imageOrderCmp)...
+//
+// The complexity here is O(N) where N is DATA.order.length rather than
+// gids.length vs. O(n nog n) for the .sort(..), but the processing overhead 
+// is significantly smaller...
+//
+// Here are a couple of test runs:
+//
+//		var t0 = Date.now()
+//		getRibbonGIDs()
+//			.slice(0, 2000)
+//			.sort(imageOrderCmp)
+//		console.log('T:', Date.now()-t0)
+//		>>> T: 4126
+// 
+//		var t0 = Date.now()
+//		fastSortGIDsByOrder(
+//			getRibbonGIDs()
+//				.slice(0,2000))
+//		console.log('T:', Date.now()-t0)
+//		>>> T: 171
+//
+// On the down side, this has some memory overhead -- ~ N - n * ref
+//
+function fastSortGIDsByOrder(gids, data){
+	data = data == null ? DATA : data
+
+	var order = data.order
+	var res = []
+
+	// insert the gids to their order positions...
+	gids.forEach(function(gid){
+		res[order.indexOf(gid)] = gid
+	})
+
+	// clear out the nulls...
+	return res.filter(function(e){
+		return e != null
+	})
+}
+
+
 // Base URL interface...
 //
 // NOTE: changing a base URL will trigger a baseURLChanged event...
@@ -638,12 +686,16 @@ function getGIDRibbonIndex(gid, data){
 // 	- number	- ribbon index
 // 	- gid
 // 	- image
-function getRibbonGIDs(a, data){
+function getRibbonGIDs(a, no_clone, data){
 	data = data == null ? DATA : data
 	if(typeof(a) == typeof(123)){
 		return data.ribbons[a].slice()
 	}
-	return data.ribbons[getGIDRibbonIndex(a, data)].slice()
+	var res = data.ribbons[getGIDRibbonIndex(a, data)]
+	if(no_clone){
+		return res
+	}
+	return res.slice()
 }
 
 
@@ -1286,6 +1338,10 @@ function makeNextFromListAction(get_closest, get_list, restrict_to_ribbon){
 
 
 // see makeNextFromListAction(..) above for documentation...
+//
+// XXX try a new technique:
+// 		- before calling getImageBefore(..) remove the curent gid form 
+// 		  target list...
 function makePrevFromListAction(get_closest, get_list, restrict_to_ribbon){
 	get_closest = get_closest == null ? getGIDBefore : get_closest
 	get_list = get_list == null ? getRibbonGIDs : get_list
@@ -2113,7 +2169,8 @@ function showImage(gid){
 // NOTE: if no_reload_viewer is true, then no re-rendering is triggered.
 function updateRibbonOrder(no_reload_viewer){
 	for(var i=0; i < DATA.ribbons.length; i++){
-		DATA.ribbons[i].sort(imageOrderCmp)
+		//DATA.ribbons[i].sort(imageOrderCmp)
+		DATA.ribbons[i] = fastSortGIDsByOrder(DATA.ribbons[i])
 	}
 	if(!no_reload_viewer){
 		reloadViewer(true)
diff --git a/ui/keybindings.js b/ui/keybindings.js
index 8de2d865..8c732b07 100755
--- a/ui/keybindings.js
+++ b/ui/keybindings.js
@@ -588,6 +588,10 @@ var KEYBOARD_CONFIG = {
 				function(){ prevBookmark() }),
 		']': doc('Next bookmarked image', 
 				function(){ nextBookmark() }),
+		'{': doc('Previous unsorted section edge', 
+				function(){ prevUnsortedSection() }),
+		'}': doc('Next unsorted section edge', 
+				function(){ nextUnsortedSection() }),
 
 		S: {
 				default: doc('Start slideshow', 
diff --git a/ui/marks.js b/ui/marks.js
index c5e4894c..5e647953 100755
--- a/ui/marks.js
+++ b/ui/marks.js
@@ -164,7 +164,7 @@ var updateSelectedImageMark = makeMarkUpdater(
 // 		not exist, as there is no way to distinguish between the two 
 // 		situations the cleanup is optional...
 function cropMarkedImages(keep_ribbons, keep_unloaded_gids){
-	var marked = MARKED.slice()//.sort(imageOrderCmp)
+	var marked = MARKED.slice()
 
 	cropDataTo(marked, keep_ribbons, keep_unloaded_gids)
 
@@ -249,7 +249,8 @@ function toggleAllMarks(action, mode){
 	if(action == 'on'){
 		var _update = function(e){
 			if(MARKED.indexOf(e) < 0){
-				insertGIDToPosition(e, MARKED)
+				//insertGIDToPosition(e, MARKED)
+				MARKED.push(e)
 				updated.push(e)
 			}
 		}
@@ -274,6 +275,8 @@ function toggleAllMarks(action, mode){
 
 	res.forEach(_update)
 
+	MARKED = fastSortGIDsByOrder(MARKED)
+
 	updateImages(updated)
 
 	$('.viewer').trigger('togglingMarks', [updated, action])
@@ -310,12 +313,14 @@ function invertImageMarks(){
 		var i = MARKED.indexOf(e)
 		if(i == -1){
 			on.push(e)
-			insertGIDToPosition(e, MARKED)
+			MARKED.push(e)
+			//insertGIDToPosition(e, MARKED)
 		} else {
 			off.push(e)
 			MARKED.splice(i, 1)
 		}
 	})
+	MARKED = fastSortGIDsByOrder(MARKED)
 	updateImages(ribbon)
 
 	$('.viewer')
@@ -348,7 +353,8 @@ function toggleMarkBlock(image){
 		}
 		// do the toggle...
 		if(state){
-			insertGIDToPosition(e, MARKED)
+			//insertGIDToPosition(e, MARKED)
+			MARKED.push(e)
 		} else {
 			MARKED.splice(MARKED.indexOf(e), 1)
 		}
@@ -364,6 +370,8 @@ function toggleMarkBlock(image){
 	var right = ribbon.slice(i+1)
 	$.each(right, _convert)
 
+	MARKED = fastSortGIDsByOrder(MARKED)
+
 	updateImages(updated)
 
 	$('.viewer')
@@ -396,7 +404,7 @@ function shiftMarkedImages(direction, mode, new_ribbon){
 	// shift all marked images...
 	} else {
 		var marked = MARKED.slice()
-		// remove all the marked images form all the ribbons...
+		// remove all the marked images form all other ribbons...
 		$.each(DATA.ribbons, function(ribbon){
 			$.each(marked, function(e){
 				var i = ribbon.indexOf(e)
@@ -420,7 +428,7 @@ function shiftMarkedImages(direction, mode, new_ribbon){
 	// add marked to existing ribbon...
 	} else {
 		cur += direction == 'next' ? 1 : -1
-		DATA.ribbons[cur] = DATA.ribbons[cur].concat(marked).sort(cmp)
+		DATA.ribbons[cur] = fastSortGIDsByOrder(DATA.ribbons[cur].concat(marked))
 	}
 	
 	// remove empty ribbons...
@@ -557,7 +565,7 @@ var loadFileMarks = makeFileLoader(
 			if(DATA.version == '2.0'){
 				setTimeout(function(){
 					var t0 = Date.now()
-					MARKED.sort(imageOrderCmp)
+					MARKED = fastSortGIDsByOrder(MARKED)
 					var t1 = Date.now()
 
 					// XXX is this the correct way to do this???
diff --git a/ui/sort.js b/ui/sort.js
index a9c9c1f3..f56622c0 100755
--- a/ui/sort.js
+++ b/ui/sort.js
@@ -177,7 +177,10 @@ function getClosestGIDs(gid){
 
 function reverseImageOrder(){
 	DATA.order.reverse()
-	updateRibbonOrder()
+	DATA.ribbons.forEach(function(r){
+		r.reverse()
+	})
+	reloadViewer(true)
 }
 
 
diff --git a/ui/tags.js b/ui/tags.js
index 301f0898..2e16f5ae 100755
--- a/ui/tags.js
+++ b/ui/tags.js
@@ -20,6 +20,10 @@ var UNSORTED_TAG = 'unsorted'
 var TAGS = {}
 
 
+var TAGS_FILE_DEFAULT = 'tags.json'
+var TAGS_FILE_PATTERN = /^[0-9]*-tags.json$/
+
+
 
 /*********************************************************************/
 
@@ -27,6 +31,8 @@ function buildTagsFromImages(tagset, images){
 	tagset = tagset == null ? TAGS : tagset
 	images = images == null ? IMAGES : images
 
+	var order = DATA.order
+
 	for(var gid in images){
 		var tags = images[gid].tags
 		// no tags in this image...
@@ -40,10 +46,19 @@ function buildTagsFromImages(tagset, images){
 			}
 			// only update if not tagged...
 			if(tagset[tag].indexOf(gid) < 0){
-				tagset[tag].push(gid)
+				// NOTE: this is cheating, but it's ~5x faster than 
+				// 		insertGIDToPosition(..) but still 10^2 slower 
+				// 		than .push(..) (unsorted tags)
+				tagset[tag][order.indexOf(gid)] = gid
 			}
 		})
 	}
+
+	// cleanup...
+	for(var tag in tagset){
+		tagset[tag] = tagset[tag].filter(function(e){ return e != null })
+	}
+
 	return tagset
 }
 
@@ -93,8 +108,6 @@ function addTag(tags, gid, tagset, images){
 			tagset[tag] = set
 		}
 		if(set.indexOf(gid) < 0){
-			//set.push(gid)
-			//set.sort()
 			insertGIDToPosition(gid, set)
 		}
 
@@ -193,7 +206,7 @@ function tagSelectAND(tags, from, no_sort, tagset){
 		return res == null 
 			? [] 
 			: res.filter(function(gid){
-				// skip unloaded from...
+				// skip unloaded...
 				return from.indexOf(gid) >= 0
 			})
 	}
@@ -231,10 +244,15 @@ function tagSelectAND(tags, from, no_sort, tagset){
 		}
 		// populate res...
 		if(gid != null && from.indexOf(gid) >= 0){
-			no_sort ? res.push(gid) : insertGIDToPosition(gid, res)
+			//no_sort == true ? res.push(gid) : insertGIDToPosition(gid, res)
+			res.push(gid)
 		}
 	})
 
+	if(!no_sort){
+		fastSortGIDsByOrder(res)
+	}
+
 	return res
 }
 
@@ -271,16 +289,11 @@ function tagSelectOR(tags, from, no_sort, tagset){
 }
 
 
-/*
-// XXX don't remember the semantics...
-function getRelatedTags(){
-}
+
+/**********************************************************************
+* List oriented tag operations...
 */
 
-
-
-/*********************************************************************/
-
 function tagList(list, tags){
 	list.forEach(function(gid){
 		addTag(tags, gid)
@@ -353,18 +366,22 @@ function unmarkTagged(tags){
 //
 // Essentially this will list tag block borders.
 //
+// NOTE: this will consider each gids's ribbon context rather than the 
+// 		straight order context...
+// XXX this is slow...
 function listTagsAtGapsFrom(tags, gids){
 	gids = gids == null ? getLoadedGIDs() : gids
 	var list = tagSelectAND(tags, gids)
 	var res = []
 
 	list.forEach(function(gid){
-		var i = gids.indexOf(gid)
+		var ribbon = DATA.ribbons[getGIDRibbonIndex(gid)]
+		var i = ribbon.indexOf(gid)
 
 		// add the current gid to the result iff one or both gids 
 		// adjacent to it are not in the list...
-		if(list.indexOf(gids[i-1]) < 0 
-				|| list.indexOf(gids[i+1]) < 0){
+		if(list.indexOf(ribbon[i-1]) < 0 
+				|| list.indexOf(ribbon[i+1]) < 0){
 			res.push(gid)
 		}
 	})
@@ -373,6 +390,44 @@ function listTagsAtGapsFrom(tags, gids){
 }
 
 
+// XXX these are still slow -- there is no need to re-index the whole 
+// 		data on each jump...
+function nextGapEdge(tags, gids){
+	var res = getGIDAfter(getImageGID(), listTagsAtGapsFrom(tags, gids))
+
+	if(res == null){
+		flashIndicator('end')
+		return getImage()
+	}
+	return showImage(res)
+}
+function prevGapEdge(tags, gids){
+	var cur = getImageGID()
+	var targets = listTagsAtGapsFrom(tags, gids)
+
+	// drop the current elem if it's in the list...
+	var i = targets.indexOf(cur)
+	if(i >= 0){
+		targets.splice(i, 1)
+	}
+
+	var res = getGIDBefore(cur, targets)
+
+	if(res == null){
+		flashIndicator('start')
+		return getImage()
+	}
+	return showImage(res)
+}
+
+
+function nextUnsortedSection(){
+	return nextGapEdge('unsorted')
+}
+function prevUnsortedSection(){
+	return prevGapEdge('unsorted')
+}
+
 
 
 /*********************************************************************/
@@ -389,6 +444,30 @@ function cropTagged(tags, keep_ribbons, keep_unloaded_gids){
 
 
 
+/**********************************************************************
+* Files...
+*/
+
+// XXX need to detect if we loaded the tags and if so not call
+// 		buildTagsFromImages(..)...
+var loadFileTags = makeFileLoader(
+		'Tags', 
+		TAGS_FILE_DEFAULT, 
+		TAGS_FILE_PATTERN, 
+		function(data){ 
+			TAGS = data
+		})
+
+
+// Save image marks to file
+var saveFileMarks = makeFileSaver(
+		TAGS_FILE_DEFAULT, 
+		function(){ 
+			return TAGS 
+		})
+
+
+
 /**********************************************************************
 * Setup...
 */
@@ -411,7 +490,7 @@ function setupTags(viewer){
 		})
 
 }
-SETUP_BINDINGS.push(setupTags)
+//SETUP_BINDINGS.push(setupTags)
 
 
 // Setup the unsorted image state managers...