diff --git a/src/karax.nim b/src/karax.nim
index ed956d8..0e58c4b 100644
--- a/src/karax.nim
+++ b/src/karax.nim
@@ -123,31 +123,20 @@ proc replaceById(id: cstring; newTree: Node) =
   #newTree.id = id
 
 proc equalsShallow(a, b: VNode): bool =
-  if a.kind != b.kind: return false
-  if a.id != b.id: return false
-  if a.key != b.key: return false
-  if a.kind == VNodeKind.text:
-    if a.text != b.text: return false
-  elif a.kind == VNodeKind.vthunk or a.kind == VNodeKind.dthunk:
-    if a.text != b.text: return false
-    if a.len != b.len: return false
-    for i in 0..<a.len:
-      if not equalsShallow(a[i], b[i]): return false
-  if not sameAttrs(a, b): return false
-  if a.class != b.class: return false
-  # XXX test event listeners here?
-  return true
-
-proc equalsTree(a, b: VNode): bool =
-  when false:
-    # hashing is too fragile now with component support:
-    if not a.validHash:
-      a.calcHash()
-    if not b.validHash:
-      b.calcHash()
-    return a.hash == b.hash
+  if a.key == -1 and b.key == -1:
+    return eq(a, b)
   else:
-    result = eq(a, b)
+    if a.kind != b.kind: return false
+    if a.id != b.id: return false
+    if a.key != b.key: return false
+    if a.kind == VNodeKind.text:
+      if a.text != b.text: return false
+    elif a.kind == VNodeKind.vthunk or a.kind == VNodeKind.dthunk:
+      if a.text != b.text: return false
+    if not sameAttrs(a, b): return false
+    if a.class != b.class: return false
+    # XXX test event listeners here?
+    return true
 
 proc updateDirtyElements(parent, current: Node, newNode: VNode) =
   if newNode.key >= 0 and isDirty(newNode.key):
@@ -164,7 +153,77 @@ proc updateDirtyElements(parent, current: Node, newNode: VNode) =
       # leave early if we know there cannot be anything left to do:
       #if dirtyCount <= 0: return
 
-proc updateElement(parent, current: Node, newNode, oldNode: VNode) =
+proc printChildren(parent: Node): cstring =
+  discard
+  # if parent != nil and parent.hasChildNodes:
+  #   var it = parent.firstChild
+  #   result = ""
+  #   while it != nil:
+  #     if it.id == nil:
+  #       result.add(" nil")
+  #     else:
+  #       result.add(" " & $it.id)
+  #     it = it.nextSibling
+
+proc printChildren(parent: VNode): cstring =
+  discard
+  # if parent != nil:
+  #   result = ""
+  #   for i in 0..parent.len-1:
+  #     if parent[i] == nil or parent[i].id == nil:
+  #       result.add(" nil")
+  #     else:
+  #       result.add(" " & $(parent[i].id))
+
+proc print(s: cstring, ident: int) =
+  discard
+  # var result = ""
+  # for i in 0..ident:
+  #   result.add "  "
+  # result.add(s)
+  # kout cstring(result)
+
+proc longestIncreasingSubsequence(a: seq[int]): seq[int] =
+  if len(a) == 0:
+    return @[]
+    
+  result.add 0
+  var parent = newSeq[int](len(a))
+  for i in 0..<len(a):
+    var j = result[len(result) - 1]
+    if a[j] < a[i]:
+      parent[i] = j
+      result.add(i)
+      continue
+    
+    var left = 0
+    var right = len(result) - 1
+
+    while left < right:
+      var mid = (left + right) div 2
+      if a[result[mid]] < a[i]:
+        left = mid + 1
+      else:
+        right = mid
+    
+    if a[i] < a[result[left]]:
+      if left > 0:
+        parent[i] = result[left - 1]
+      result[left] = i
+    
+  var pos = len(result)
+  var v = result[pos - 1]
+  while pos > 0:
+    result[pos] = v
+    v = parent[v]
+    dec pos
+
+proc updateElement(parent, current: Node, newNode, oldNode: VNode, ident: int = 0) =
+  if newNode.key != -1:
+    kout cstring($newNode.key)
+  if oldNode.key != -1:
+    kout cstring($oldNode.key)
+  newNode.dom = oldNode.dom
   if not equalsShallow(newNode, oldNode):
     detach(oldNode)
     let n = vnodeToDom(newNode)
@@ -188,36 +247,177 @@ proc updateElement(parent, current: Node, newNode, oldNode: VNode) =
           detach(oldNode[i])
           current.removeChild(current.lastChild)
     else:
-      var commonPrefix = 0
-      while commonPrefix < minLength and
-          equalsTree(newNode[commonPrefix], oldNode[commonPrefix]):
-        inc commonPrefix
+      #kout cstring("start") 
+      print("----------------", ident)
+      print("----------------", ident)
+      var before = printChildren(current)
 
-      var oldPos = oldLength - 1
-      var newPos = newLength - 1
-      while oldPos >= commonPrefix and newPos >= commonPrefix and
-          equalsTree(newNode[newPos], oldNode[oldPos]):
-        dec oldPos
-        dec newPos
+      # maximal common prefix
+      var left = 0
+      while left < minLength and equalsShallow(newNode[left], oldNode[left]):
+        updateElement(current, oldNode[left].dom, newNode[left], oldNode[left], ident + 1)
+        inc left
 
-      var pos = min(oldPos, newPos) + 1
-      for i in commonPrefix..pos-1:
-        updateElement(current, current.childNodes[i], newNode[i], oldNode[i])
+      # maximal common suffix
+      var rightOld = oldLength - 1
+      var rightNew = newLength - 1
+      while rightOld >= left and rightNew >= left and equalsShallow(newNode[rightNew], oldNode[rightOld]):
+        updateElement(current, oldNode[rightOld].dom, newNode[rightNew], oldNode[rightOld], ident + 1)
+        dec rightOld
+        dec rightNew
 
-      var nextChildPos = oldPos + 1
-      while pos <= newPos:
-        if nextChildPos == oldLength:
-          current.appendChild(vnodeToDom(newNode[pos]))
+      var leftOld = left
+      var leftNew = left
+      
+     
+      var flag = false
+      #if rightOld >= leftOld and rightNew >= leftNew and equalsShallow(oldNode[leftOld], newNode[rightNew]):
+      print("current", ident)
+      print(printChildren(current), ident)
+      print("oldNode", ident)
+      print(printChildren(oldNode), ident)
+      print("newNode", ident)
+      print(printChildren(newNode), ident)
+      flag = true
+      
+      # cross comparing
+      while rightOld >= leftOld and rightNew >= leftNew and equalsShallow(oldNode[leftOld], newNode[rightNew]):
+        print($oldNode[leftOld].id & " " & $newNode[rightNew].id, ident)
+        print("pos: " & $leftOld & " " & $rightNew, ident)
+
+        var nextNode: Node = nil
+        if rightNew + 1 < newLength:
+          nextNode = newNode[rightNew + 1].dom
+        print("update", ident)
+        updateElement(current, oldNode[leftOld].dom, newNode[rightNew], oldNode[leftOld], ident + 1)
+        print("update", ident)
+        if nextNode == nil:
+          current.appendChild(oldNode[leftOld].dom)
+          print("append", ident)
         else:
-          current.insertBefore(vnodeToDom(newNode[pos]), current.childNodes[nextChildPos])
-        # added new Node, so old state of VDOM have one more Node
-        inc oldLength
-        inc pos
-        inc nextChildPos
+          print("insertBefore", ident)
+          current.insertBefore(oldNode[leftOld].dom, nextNode)
+        print($oldNode[leftOld], ident)
+        inc leftOld
+        dec rightNew
 
-      for i in pos..oldPos:
-        detach(oldNode[i])
-        current.removeChild(current.childNodes[pos])
+      while rightOld >= leftOld and rightNew >= leftNew and equalsShallow(oldNode[rightOld], newNode[leftNew]):
+        var nextNode: Node = oldNode[leftOld].dom
+        updateElement(current, oldNode[rightOld].dom, newNode[leftNew], oldNode[rightOld], ident + 1)
+        current.insertBefore(oldNode[rightOld].dom, nextNode)
+        inc leftNew
+        dec rightOld
+
+      if flag:
+        print("after", ident)
+        print(printChildren(current), ident)
+
+      var isKeyed = true
+      for i in leftNew..rightNew:
+        if newNode[i].key == -1:
+          isKeyed = false
+          break
+
+      for i in leftOld..rightOld:
+        if oldNode[i].key == -1:
+          isKeyed = false
+        if not isKeyed:
+          break
+
+      if rightNew - leftNew + 1 + rightOld - leftOld + 1 == 0:
+        isKeyed = false
+
+      
+      if isKeyed:
+        if rightNew > leftNew:
+          # remove redundant old nodes
+          for i in leftOld..rightOld:
+            current.removeChild(oldNode[i].dom)
+            detach(oldNode[i])
+        else:
+          # permute elements using LIS
+          var positionByKey = newJDict[VKey, int]()
+          var positions = newSeq[int]()
+          for i in leftOld..rightOld:
+            positionByKey[oldNode[i].key] = i
+          for i in leftNew..rightNew:
+            if positionByKey.contains(newNode[i].key):
+              positions.add positionByKey[newNode[i].key]
+          
+          #if len(positions) > 0:
+          # kout cstring("new segment len = " & $(rightNew - leftNew + 1))
+          # kout cstring("old segment len = " & $(rightOld - leftOld + 1))
+          # var t = ""
+          # for i in 0..<len(positions):
+          #   t.add($positions[i] & " ")
+          # kout cstring(t)
+
+          var lis = longestIncreasingSubsequence(positions)
+          var lisPos = 0
+          var isNotRedundant = newSeq[bool](rightOld - leftOld + 1)
+          for i in leftNew..rightNew:
+            if lisPos < len(lis):
+              var index = lis[lisPos]
+              if oldNode[index].key == newNode[i].key:
+                isNotRedundant[index - leftOld] = true
+                updateElement(current, oldNode[index].dom, newNode[i], oldNode[index], ident + 1)
+                inc lisPos
+              else:
+                if positionByKey.contains(newNode[i].key):
+                  var oldPos = positionByKey[newNode[i].key]
+                  isNotRedundant[oldPos - leftOld] = true
+                  current.insertBefore(oldNode[oldPos].dom, oldNode[index].dom)
+                else:
+                  current.insertBefore(vnodeToDom(newNode[i]), oldNode[index].dom)
+            else:
+              if positionByKey.contains(newNode[i].key):
+                var oldPos = positionByKey[newNode[i].key]
+                isNotRedundant[oldPos - leftOld] = true
+                current.appendChild(oldNode[oldPos].dom)
+              else:
+                current.appendChild(vnodeToDom(newNode[i]))
+            
+            # remove redundant old nodes
+            for i in leftOld..rightOld:
+              if not isNotRedundant[i]:
+                current.removeChild(oldNode[i].dom)
+      else:
+        # simply diff 
+        print($leftOld & " " & $rightOld & " " & $leftNew & " " & $rightNew, ident)
+        while rightOld >= leftOld and rightNew >= leftNew:
+          updateElement(current, oldNode[leftOld].dom, newNode[leftNew], oldNode[leftOld], ident + 1)
+          inc leftNew
+          inc leftOld
+        
+        print("TEMP", ident)
+        print(printChildren(current), ident)
+        print($leftOld & " " & $rightOld & " " & $leftNew & " " & $rightNew, ident)
+        print("other part start", ident)
+        var isPushBack = (rightNew + 1 == newLength)
+        var nextNode: Node = nil
+        if not isPushBack:
+          print($(rightNew + 1), ident)
+          nextNode = newNode[rightNew + 1].dom
+        while leftNew <= rightNew:
+          var node = vnodeToDom(newNode[leftNew])
+          if isPushBack:
+            current.appendChild(node)
+          else:
+            current.insertBefore(node, nextNode)
+          inc leftNew
+        print("other part finish", ident)
+
+        for i in leftOld..rightOld:
+          current.removeChild(oldNode[i].dom)
+          detach(oldNode[i])
+
+        print("----------------", ident)
+        print("before", ident)
+        print(before, ident)
+        print("finish", ident)
+        print(printChildren(current), ident)
+        print("----------------", ident)
+        print("----------------", ident)
 
 when false:
   var drawTimeout: Timeout
@@ -256,6 +456,8 @@ proc redraw*() =
   else:
     dodraw()
 
+proc redrawForce*() = dodraw()
+
 proc init(ev: Event) =
   reqFrame(dodraw)
 
@@ -263,6 +465,12 @@ proc setRenderer*(renderer: proc (): VNode) =
   dorender = renderer
   window.onload = init
 
+proc setRendererOnly*(renderer: proc (): VNode) =
+  dorender = renderer
+
+proc setOnloadOnly*() =
+  window.onload = init
+
 proc addEventHandler*(n: VNode; k: EventKind; action: EventHandler) =
   ## Implements the foundation of Karax's event management.
   ## Karax DSL transforms ``tag(onEvent = handler)`` to
diff --git a/src/karaxdsl.nim b/src/karaxdsl.nim
index 5ba525a..5553d8f 100644
--- a/src/karaxdsl.nim
+++ b/src/karaxdsl.nim
@@ -4,7 +4,7 @@ from strutils import startsWith, toLowerAscii
 
 const
   StmtContext = ["kout", "inc", "echo", "dec", "!"]
-  SpecialAttrs = ["id", "class", "value", "key"]
+  SpecialAttrs = ["id", "class", "value", "key", "track"]
 
 proc getName(n: NimNode): string =
   case n.kind
diff --git a/src/vdom.nim b/src/vdom.nim
index 25f6c12..a80fc10 100644
--- a/src/vdom.nim
+++ b/src/vdom.nim
@@ -102,12 +102,14 @@ type
     kind*: VNodeKind
     key*: VKey
     id*, class*, text*: cstring
+    track*: int
     kids: seq[VNode]
     # even index: key, odd index: value; done this way for memory efficiency:
     attrs: seq[cstring]
     events*: seq[(EventKind, EventHandler)]
-    hash*: Hash
-    validHash*: bool
+    when false:
+      hash*: Hash
+      validHash*: bool
     dom*: Node ## the attached real DOM node. Can be 'nil' if the virtual node
                ## is not part of the virtual DOM anymore.
 
@@ -146,7 +148,11 @@ proc eq*(a, b: VNode): bool =
 
 proc setAttr*(n: VNode; key: cstring; val: cstring = "") =
   if n.attrs.isNil:
-    n.attrs = @[key, val]
+    when true:
+      let x = @[key, val]
+      shallowCopy n.attrs, x
+    else:
+      n.attrs = @[key, val]
   else:
     for i in countup(0, n.attrs.len-2, 2):
       if n.attrs[i] == key:
@@ -161,6 +167,7 @@ proc getAttr*(n: VNode; key: cstring): cstring =
 
 proc len*(x: VNode): int = x.kids.len
 proc `[]`*(x: VNode; idx: int): VNode = x.kids[idx]
+proc `[]=`*(x: VNode; idx: int; y: VNode) = x.kids[idx] = y
 proc add*(parent, kid: VNode) = parent.kids.add kid
 proc newVNode*(kind: VNodeKind): VNode = VNode(kind: kind, key: -1)
 
@@ -216,32 +223,33 @@ proc toString*(n: VNode; result: var string; indent: int) =
   for i in 1..indent: result.add ' '
   result.add "\L</" & $n.kind & ">"
 
-proc calcHash*(n: VNode) =
-  if n.validHash: return
-  n.validHash = true
-  var h: Hash = ord n.kind
-  if n.id != nil:
-    h &= "id"
-    h &= n.id
-  if n.class != nil:
-    h &= "class"
-    h &= n.class
-  if n.key >= 0:
-    h &= "k"
-    h &= n.key
-  for k, v in attrs(n):
-    h &= " "
-    h &= k
-    h &= "="
-    h &= v
-  if n.kind == VNodeKind.text or n.text != nil:
-    h &= "t"
-    h &= n.text
-  else:
-    for child in items(n):
-      calcHash(child)
-      h &= child.hash
-  n.hash = h
+when false:
+  proc calcHash*(n: VNode) =
+    if n.validHash: return
+    n.validHash = true
+    var h: Hash = ord n.kind
+    if n.id != nil:
+      h &= "id"
+      h &= n.id
+    if n.class != nil:
+      h &= "class"
+      h &= n.class
+    if n.key >= 0:
+      h &= "k"
+      h &= n.key
+    for k, v in attrs(n):
+      h &= " "
+      h &= k
+      h &= "="
+      h &= v
+    if n.kind == VNodeKind.text or n.text != nil:
+      h &= "t"
+      h &= n.text
+    else:
+      for child in items(n):
+        calcHash(child)
+        h &= child.hash
+    n.hash = h
 
 proc `$`*(n: VNode): cstring =
   var res = ""
diff --git a/tests/diffDomTests.html b/tests/diffDomTests.html
index 5ecf130..cb6ab28 100644
--- a/tests/diffDomTests.html
+++ b/tests/diffDomTests.html
@@ -3,7 +3,6 @@
 <html>
 <head>
   <title>Diff dom tests</title>
-  <link rel="stylesheet" href="style.css">
 </head>
 
 <body id="body">
diff --git a/tests/diffDomTests.nim b/tests/diffDomTests.nim
index 7fdcf85..ee907c8 100644
--- a/tests/diffDomTests.nim
+++ b/tests/diffDomTests.nim
@@ -41,7 +41,7 @@ proc test1() =
 proc check2() =
     let result = checkOrder(@[8, 0, 1, 2, 3, 4, 7, 5])
     if result:
-        results.add cstring"test1 - OK"
+        results.add cstring"test2 - OK"
     else:
         results.add cstring"test2 - FAIL"
 
@@ -83,16 +83,16 @@ proc test4() =
     timeout = setTimeout(check4, 20)
 
 proc check5() =
-    let result = checkOrder(@[0, 1, 3, 5, 4, 5])
+    let result = checkOrder(@[0, 1, 3, 5, 4, 8])
     if result:
         results.add cstring"test5 - OK"
     else:
         results.add cstring"test5 - FAIL"
 
-# result: 0 1 3 5 4 5
+# result: 0 1 3 5 4 8
 proc test5() =
     results.add cstring"test5 started"
-    entries = @[cstring("0"), cstring("1"), cstring("3"), cstring("5"), cstring("4"), cstring("5") ]
+    entries = @[cstring("0"), cstring("1"), cstring("3"), cstring("5"), cstring("4"), cstring("8") ]
     redraw()
     timeout = setTimeout(check5, 20)
 
@@ -127,14 +127,14 @@ proc test7() =
 
 proc createEntry(id: int): VNode =
   result = buildHtml():
-    button(id="" & $id):
+    button(id="" & $id, key = id):
         text $id
 
 proc createDom(): VNode =
     result = buildHtml(tdiv()):
         ul(id="ul"):
             for e in entries:
-                createEntry(parseInt(e))
+                createEntry(jstrutils.parseInt(e))
         for r in results:
             tdiv:
                 text r
diff --git a/uibench/index.html b/uibench/index.html
new file mode 100644
index 0000000..5b2cb4c
--- /dev/null
+++ b/uibench/index.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<html lang="en">
+<head>
+  <meta charset="UTF-8">
+  <link href="https://localvoid.github.io/uibench-base/0.1.0/styles.css" rel="stylesheet" />
+  <title>UI Benchmark: React</title>
+</head>
+<body>
+
+<div id="ROOT"></div>
+
+<script src="https://localvoid.github.io/uibench-base/0.1.0/uibench.js"></script>
+<script src="nimcache/nim_uibench.js" type="text/javascript"></script>
+
+</body>
+</html>
diff --git a/uibench/nim_uibench.nim b/uibench/nim_uibench.nim
new file mode 100644
index 0000000..3d1f078
--- /dev/null
+++ b/uibench/nim_uibench.nim
@@ -0,0 +1,105 @@
+import dom, vdom, karax, karaxdsl, jdict, jstrutils, kajax
+
+type
+    HomeState {.importc.} = ref object
+    TableItemState {.importc.} = ref object
+        id: int
+        active: bool
+        props: seq[cstring]
+    TableState {.importc.} = ref object
+        items: seq[TableItemState]
+    AnimBoxState {.importc.} = ref object
+        id: int
+        time: int
+    AnimState {.importc.} = ref object
+        items: seq[AnimBoxState]
+    TreeNodeState {.importc.} = ref object
+        id: int
+        container: bool
+        children: seq[TreeNodeState]
+    TreeState {.importc.} = ref object
+        root: TreeNodeState
+    AppState {.importc.} = ref object
+        location: cstring
+        home: HomeState
+        table: TableState
+        anim: AnimState
+        tree: TreeState
+
+var appState: AppState
+
+proc createTableCell(id: cstring): VNode =
+    proc tableCellClick(ev: karax.Event; n: VNode) =
+        kout "Clicked" & id
+    result = buildHtml(td(class="TableCell", onclick=tableCellClick)):
+        text id
+
+proc createTableRow(item: TableItemState): VNode =
+    let className = if item.active: cstring"TableRow active" else: cstring"TableRow"
+    result = buildHtml(tr(class=className, `data-id` = &item.id)):
+        createTableCell("#" & &item.id)
+        for i in 0..<len(item.props):
+            createTableCell(item.props[i])
+
+proc tableCreateVNode(data: TableState): VNode =
+    result = buildHtml(table(class="Table")):
+        tbody:
+            for child in data.items:
+                createTableRow(child)
+
+proc createAnimBox(item: AnimBoxState): VNode =
+    let time = item.time
+    let t10 = time mod 10
+    let color = float(t10) / 10
+    let divStyles = cstring"border-radius: " & &t10 &
+         "px; background: rgba(0,0,0," & cstring($color) & ")"
+    result = flatHtml(tdiv(class="AnimBox", `data-id` = &item.id, style=divStyles))
+
+proc animCreateVNode(data: AnimState): VNode =
+    result = buildHtml(tdiv(class="Anim")):
+        for child in data.items:
+            createAnimBox(child)
+
+proc createTreeNode(data: TreeNodeState): VNode =
+    result = buildHtml(ul(class="TreeNode")):
+        for n in data.children:
+            if n.container:
+                createTreeNode(n)
+            else:
+                li(class="TreeLeaf"):
+                    text &n.id
+
+proc treeCreateVNode(data: TreeState): VNode =
+    result = buildHtml(tdiv(class="Tree")):
+        createTreeNode(data.root)
+
+proc update(): VNode =
+    assert appState != nil
+    let location = appState.location
+    var children: VNode = nil
+    if location == cstring"table":
+        children = tableCreateVNode(appState.table)
+    elif location == cstring"anim":
+        children = animCreateVNode(appState.anim)
+    elif location == cstring"tree":
+        children = treeCreateVNode(appState.tree)
+    result = buildHtml():
+        tdiv(class="Main"):
+            children
+
+proc a(state: AppState) =
+    appState = state
+    redrawForce()
+
+proc myToJson[T](x: T): cstring {.importcpp: "JSON.stringify(#, null, ' ')".}
+
+proc b(samples: RootRef) =
+    document.body.innerHTML = cstring"<pre>" & myToJson(samples) & cstring"</pre>"
+
+proc init*(a: cstring, b: cstring) {.importc: "uibench.init", nodecl.}
+proc run*(a: proc(state: AppState), b: proc(samples: RootRef)) {.importc: "uibench.run", nodecl.}
+
+init(cstring"Nim-karax", cstring"0.6.1")
+
+setRendererOnly update
+run(a, b)
\ No newline at end of file
diff --git a/uibench/nim_uibench.nims b/uibench/nim_uibench.nims
new file mode 100644
index 0000000..532b206
--- /dev/null
+++ b/uibench/nim_uibench.nims
@@ -0,0 +1 @@
+--path: "../src"