diff --git a/bower.json b/bower.json
index f0c2326..9b7fe82 100644
--- a/bower.json
+++ b/bower.json
@@ -22,6 +22,7 @@
     "bootstrap": "~3.3.4",
     "sweetalert": "~0.5.0",
     "angular": "~1.3.15",
-    "angular-ui-router": "~0.2.13"
+    "angular-ui-router": "~0.2.13",
+    "async": "~0.9.2"
   }
 }
diff --git a/gulpfile.js b/gulpfile.js
index b41d89e..7c5d339 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -35,6 +35,7 @@ gulp.task('js',function(){
   jsFiles = ["src/*.js",
       "bower_components/jquery/dist/jquery.js",
       "bower_components/moment/moment.js",
+      "bower_components/async/lib/async.js",
       "bower_components/bootstrap/dist/js/bootstrap.js",
       "bower_components/bootstrap/js/collapse.js",
       "bower_components/angular/angular.js",
diff --git a/src/PBSlib.coffee b/src/PBSlib.coffee
index fc5b89e..31388b9 100644
--- a/src/PBSlib.coffee
+++ b/src/PBSlib.coffee
@@ -1,6 +1,7 @@
 class PBS
   constructor: (@list, @verbose) ->
     @days = []
+    @verbose = yes
     @criticalPaths = []
 
   log: (x...) ->
@@ -25,68 +26,89 @@ class PBS
     return item
 
   # Compute the item's end day 
-  calculateEndDay: (item) =>
-    if !item.startDay?
+  calculateEndDay: (item,cb) =>
+    if item.endDay? then cb null, item.endDay
+    else if !item.startDay?
       @log "calculating start day of",item.id
-      item.startDay = @calculateStartDay item
-    @log "start day of",item.id,"is",item.startDay
-    item.endDay = item.startDay + item.duration
-    @log "end day of",item.id,"is",item.endDay
-    @insertDay item.endDay
-    return item.endDay
+      @calculateStartDay item, => @calculateEndDay item, cb
+    else
+      @log "start day of",item.id,"is",item.startDay
+      item.endDay = item.startDay + item.duration
+      @log "end day of",item.id,"is",item.endDay
+      @insertDay item.endDay
+      cb null, item.endDay
 
   # Find out which day the activity starts
-  calculateStartDay: (item) =>
-    if !item.depends? or item.depends.length is 0
+  calculateStartDay: (item,cb) =>
+    if item.startDay? then cb null, item.startDay
+    else if !item.depends? or item.depends.length is 0
       @insertDay 0
-      return item.startDay = 0
-    item.startDay = @maxa item.depends.map(@toActivity).map @calculateEndDay
-    @log "start day of",item.id,"is",item.startDay
-    # write max delay time to each depend
-    for j,x of item.depends
-      @log "checking permittedDelay to dependency", x, "of", item
-      i = @toActivity x
-      if !i.dependant? then i.dependant = [item.id]
-      else i.dependant.push item.id
-      if !i.permittedDelay?
-        i.permittedDelay = item.startDay - @calculateEndDay i
-        @log "written permittedDelay to dependency", x, "of", item, "as", i.permittedDelay
-      else @log "aborting permittedDelay: already calculated"
-      @log "permitted delay of",x,"is",i.permittedDelay
-    @insertDay item.startDay
-    return item.startDay
+      cb null, item.startDay = 0
+    else
+      async.map item.depends.map(@toActivity), @calculateEndDay.bind(@), (er, r) =>
+        item.startDay = @maxa r
+        @log "start day of",item.id,"is",item.startDay
+        # write max delay time to each depend
+        checkPermittedDelay = (x,c) =>
+          @log "checking permittedDelay to dependency", x, "of", item
+          i = @toActivity x
+          if !i.dependant? then i.dependant = [item.id]
+          else i.dependant.push item.id
+          if !i.permittedDelay?
+            @calculateEndDay i, (e,d) =>
+              i.permittedDelay = item.startDay - d
+              @log "written permittedDelay to dependency", x, "of", item, "as", i.permittedDelay
+              @log "permitted delay of",x,"is",i.permittedDelay
+              c()
+          else
+            @log "aborting permittedDelay: already calculated"
+            @log "permitted delay of",x,"is",i.permittedDelay
+            c()
+        async.each item.depends, checkPermittedDelay.bind(@), =>
+          @insertDay item.startDay
+          cb null, item.startDay
 
-  calculateDelays: (item) =>
-    if !item.dependant? or item.dependant.length is 0 then return no
-    lowestFDelay = 0; fDelay = no; cDelay = 0
-    for j,i of item.dependant
-      x = @toActivity i
-      if !isNaN(x.permittedDelay) or x.permittedDelay < lowestFDelay or fDelay is no
-        @log "activity", i, "dependant on", item.id, "has the lowest delay for now ("+(x.permittedDelay or 0)+")"
-        lowestFDelay = x.permittedDelay or 0
-        cDelay = x.chainedDelay or 0
-        fDelay = yes
-    olDelay = item.chainedDelay
-    item.chainedDelay = lowestFDelay + cDelay
-    @log "chained delay of", item.id, "is", item.chainedDelay
-    return item.chainedDelay isnt olDelay
+  calculateDelays: (item,cb) =>
+    if !item.dependant? or item.dependant.length is 0 then cb null, no
+    else
+      lowestFDelay = 0; fDelay = no; cDelay = 0
+      checkDependant = (i,c) =>
+        x = @toActivity i
+        if !isNaN(x.permittedDelay) or x.permittedDelay < lowestFDelay or fDelay is no
+          @log "activity", i, "dependant on", item.id, "has the lowest delay for now ("+(x.permittedDelay or 0)+")"
+          lowestFDelay = x.permittedDelay or 0
+          cDelay = x.chainedDelay or 0
+          fDelay = yes
+          c()
+      async.each item.dependant, checkDependant.bind(@), =>
+        olDelay = item.chainedDelay
+        item.chainedDelay = lowestFDelay + cDelay
+        @log "chained delay of", item.id, "is", item.chainedDelay
+        cb null, item.chainedDelay isnt olDelay
 
-  calculateCriticalPaths: (path) ->
+  calculateCriticalPaths: (path,cb) ->
     @log "calculating path from",path
     lastID = path[path.length - 1]
     last = @toActivity lastID
     if last.dependant? and last.dependant.length > 0
-      last.dependant.forEach (x) =>
+      checkDependant = (x,cb2) =>
         ii = @toActivity x
         delay = ii.permittedDelay or 0
         if delay is 0
-          @calculateCriticalPaths path.concat x
+          cb2 null, yes
+          @calculateCriticalPaths path.concat(x), cb
         else
           @log "dead end at", lastID, "-->", x, "because delay is", delay
+          cb2 null, no
+      async.each last.dependant, checkDependant.bind(@), (a,b) -> return
     else
-      path.forEach (x) => @toActivity(x).critical = yes
-      @log "calculated path", path
-      @criticalPaths.push path
+      setCritical = (x,c) =>
+        @toActivity(x).critical = yes
+        c null, yes
+      async.each path, setCritical.bind(@), =>
+        @log "calculated path", path
+        @criticalPaths.push path
+        cb null, path
 
   # Find out which activity has the highest id
   highestID: => return @maxa(@list.map (x) -> x.id)
@@ -100,26 +122,41 @@ class PBS
   setData: (data) ->
     @list = data
     return @
-
+  
   calculate: (options,cb) ->
-    h = @highestID()
-    for x,i in @list
-      @log '('+x.id+'/'+h+')'
-      @calculateEndDay x
-    finished = no; i = 0
-    while !finished
-      i++; finished = yes
-      for x,i in @list
-        if @calculateDelays x
-          finished = no
-    @log "Done calculating delays. Took", i, "iterations"
-    for x,i in @list
-      if !x.depends? or x.depends.length is 0
-        @calculateCriticalPaths [x.id]
-    results = activities: @list, days: @days, criticalPaths: @criticalPaths
-    if options?.json
-      if cb? then cb(JSON.stringify results)
-      JSON.stringify results
-    else
-      if cb? then cb(results)
-      results
+    @log "(Step 1) calculating startDay, endDay, freeDelay"
+    async.each @list, @calculateEndDay.bind(@), =>
+      @log "(Step 2) Starting chained delay calculations."
+      cont = yes; i = 0
+      notDone = ->
+        console.log cont
+        cont
+      chainedDelayChanged = (x,res) =>
+        i++
+        cont = no
+        @calculateDelays x, (e,r) =>
+          @log "cDelay calc result:",r
+          res null, r
+      calculateAllDelays = (cb2) =>
+        async.map @list, chainedDelayChanged, (err,r) ->
+          iterator = (acc,x,cb3) ->
+            if x
+              cb3 null, yes
+            else cb3 null, acc
+          async.reduce r, no, iterator, (err,res) ->
+            cont = res
+            cb2 null
+      #TODO: check WHILST
+      async.whilst notDone, calculateAllDelays, =>
+        @log "Done calculating delays. Took", i, "iterations"
+        #TODO: check THIS vvvvv
+        calculateCriticalPathIfApplicable = (x, c) =>
+          if !x.depends? or x.depends.length is 0
+            @calculateCriticalPaths [x.id], c
+        async.each @list, calculateCriticalPathIfApplicable.bind(@), =>
+          results = activities: @list, days: @days, criticalPaths: @criticalPaths
+          @log "DONE:", results
+          if options?.json
+            cb JSON.stringify results
+          else
+            cb results
diff --git a/src/app.coffee b/src/app.coffee
index 46db041..eaedbf9 100644
--- a/src/app.coffee
+++ b/src/app.coffee
@@ -46,13 +46,15 @@ pertController = ($scope) ->
       localStorage.setItem 'ganttpert', sdata
       unless options.silent
         swal 'Ok', 'Data updated', 'success'
-      $scope.pbs = new PBS(data).calculate()
-      $scope.$broadcast 'dataChanged'
+      $scope.pbs = new PBS(data).calculate {}, ->
+        $scope.$broadcast 'dataChanged'
     catch e
       swal 'Error', e, 'error'
 
-  $scope.fromLocalStorage = (options) ->
+  $scope.fromLocalStorage = (options,cb) ->
     options = options || {}
+    if options.call? then cb = options
+    else unless cb?.call? then return console.log "fromLocalStorage called without callback"
     data = localStorage.getItem options.name || 'ganttpert'
     if data is null then data = "[]"
     try
@@ -63,13 +65,15 @@ pertController = ($scope) ->
         swal 'JSON Error', e, 'error'
       if options.raw
         #console.log 'Loading: []'
-        return []
+        cb []
       else
         #console.log 'Loading: {list: [], days: []}'
-        return list: [], days: []
+        cb list: [], days: []
     if options.raw
       #console.log 'Loading: '+jdata
-      return jdata
+      cb jdata
     else
       #console.log 'Loading: '+$scope.pbs
-      return $scope.pbs ?= new PBS(jdata).calculate()
+      new PBS(jdata).calculate (x) ->
+        $scope.pbs = x
+        cb x
diff --git a/src/controllers.coffee b/src/controllers.coffee
index f50b620..1697c9d 100644
--- a/src/controllers.coffee
+++ b/src/controllers.coffee
@@ -1,9 +1,8 @@
 pertApp.controller 'tableController', ($scope) ->
   $scope.list = []
   $scope.refreshTable = ->
-    ls = $scope.fromLocalStorage()
-    if ls?
-      $scope.list = ls.activities
+    $scope.fromLocalStorage (ls) ->
+      if ls? then $scope.list = ls.activities
   $scope.$on 'dataChanged', $scope.refreshTable
   $scope.refreshTable()
 
@@ -32,7 +31,7 @@ pertApp.controller 'pertDiagController', ($scope) ->
       network = new vis.Network (document.getElementById 'pertDiagram'), { nodes: nodes, edges: connections }, options
   $scope.rebuild = ->
     console.log 'rebuild'
-    $scope.buildGraph $scope.fromLocalStorage()
+    $scope.fromLocalStorage (r) -> $scope.buildGraph r
   $scope.$on 'dataChanged', $scope.rebuild
   $scope.rebuild()
 
@@ -47,8 +46,8 @@ pertApp.controller 'ganttDiagController', ($scope) ->
     if !data? then return
     timeline = new vis.Timeline (document.getElementById 'timeline'), ($scope.toDates data.activities), {}
   $scope.$on 'dataChanged', ->
-    $scope.buildTimeline $scope.fromLocalStorage()
-  $scope.buildTimeline $scope.fromLocalStorage()
+    $scope.fromLocalStorage (r) -> $scope.buildTimeline r
+  $scope.fromLocalStorage (r) -> $scope.buildTimeline r
 
 pertApp.controller 'rawEditorController', ($scope) ->
   $scope.reset = ->
@@ -60,10 +59,9 @@ pertApp.controller 'rawEditorController', ($scope) ->
       swal 'Invalid Data', e, 'error'
     $scope.toLocalStorage data
   $scope.reloadData = ->
-    $scope.taData = JSON.stringify $scope.fromLocalStorage silent: yes, raw: yes
-  $scope.$on 'dataChanged', ->
-    $scope.reloadData()
-    #$('#ta').val JSON.stringify $scope.fromLocalStorage silent: yes, raw: yes
+    $scope.fromLocalStorage { silent: yes, raw: yes }, (x) ->
+      $scope.taData = JSON.stringify x
+  $scope.$on 'dataChanged', -> $scope.reloadData()
   $scope.reloadData()
 
 pertApp.controller 'editorController', ($scope) ->
@@ -77,18 +75,18 @@ pertApp.controller 'editorController', ($scope) ->
     swal 'Ops', 'could not find '+id, 'warning'
 
   $scope.delete = (index,id) ->
-    newdata = $scope.fromLocalStorage raw: yes
-    l = []
-    if id? then for i,j of newdata
-      if id isnt j.id
-        l.push j
-    else for i,j of newdata
-      if parseInt(i) isnt index
-        l.push j
-    diff = newdata.length - l.length
-    $scope.toLocalStorage l, silent: yes
-    if diff isnt 1
-      swal 'Done', diff+' item(s) deleted', 'warning'
+    $scope.fromLocalStorage { raw: yes }, (newdata) ->
+      l = []
+      if id? then for i,j of newdata
+        if id isnt j.id
+          l.push j
+      else for i,j of newdata
+        if parseInt(i) isnt index
+          l.push j
+      diff = newdata.length - l.length
+      $scope.toLocalStorage l, silent: yes
+      if diff isnt 1
+        swal 'Done', diff+' item(s) deleted', 'warning'
 
   $scope.addNew = (id, dur, deps) ->
     dur ?= $('#new-duration').val().trim()
@@ -109,14 +107,14 @@ pertApp.controller 'editorController', ($scope) ->
         unless isNaN dep
           deps[i] = parseInt dep
       catch e
-    newdata = $scope.fromLocalStorage silent: yes, raw: yes
-    if !newdata? or newdata is null or !newdata.push?
-      newdata = []
-    newdata.push { id: id, duration: dur, depends: deps }
-    $scope.toLocalStorage newdata, silent: yes
+    $scope.fromLocalStorage { silent: yes, raw: yes }, (newdata) ->
+      if !newdata? or newdata is null or !newdata.push?
+        newdata = []
+      newdata.push { id: id, duration: dur, depends: deps }
+      $scope.toLocalStorage newdata, silent: yes
   
   $scope.refreshEditor = ->
-    data = $scope.fromLocalStorage { silent: yes, raw: yes }
-    $scope.list = data || []
+    $scope.fromLocalStorage { silent: yes, raw: yes }, (data) ->
+      $scope.list = data || []
   $scope.$on 'dataChanged', $scope.refreshEditor
   $scope.refreshEditor()
diff --git a/src/index.html b/src/index.html
index 47df66a..18f044d 100644
--- a/src/index.html
+++ b/src/index.html
@@ -9,6 +9,7 @@
     <link rel="stylesheet" href="style.css">
     <link rel="stylesheet" href="sweet-alert.css">
     <script src="jquery.js"></script>
+    <script src="async.js"></script>
     <script src="sweet-alert.js"></script>
     <script src="angular.js"></script>
     <script src="bootstrap.js"></script>