diff --git a/src/Binary/Encoder.js b/src/Binary/Encoder.js
index f080ccaf..4fbeff4b 100644
--- a/src/Binary/Encoder.js
+++ b/src/Binary/Encoder.js
@@ -6,6 +6,7 @@ const bits8 = 0b11111111
 
 export default class BinaryEncoder {
   constructor () {
+    // TODO: implement chained Uint8Array buffers instead of Array buffer
     this.data = []
   }
 
diff --git a/src/Connector.js b/src/Connector.js
index dbf85047..b0f6c65c 100644
--- a/src/Connector.js
+++ b/src/Connector.js
@@ -88,6 +88,7 @@ export default class AbstractConnector {
       isSynced: false,
       role: role,
       processAfterAuth: [],
+      processAfterSync: [],
       auth: auth || null,
       receivedSyncStep2: false
     })
@@ -122,17 +123,15 @@ export default class AbstractConnector {
   }
 
   _fireIsSyncedListeners () {
-    setTimeout(() => {
-      if (!this.isSynced) {
-        this.isSynced = true
-        // It is safer to remove this!
-        // call whensynced listeners
-        for (var f of this.whenSyncedListeners) {
-          f()
-        }
-        this.whenSyncedListeners = []
+    if (!this.isSynced) {
+      this.isSynced = true
+      // It is safer to remove this!
+      // call whensynced listeners
+      for (var f of this.whenSyncedListeners) {
+        f()
       }
-    }, 0)
+      this.whenSyncedListeners = []
+    }
   }
 
   send (uid, buffer) {
@@ -237,16 +236,16 @@ export default class AbstractConnector {
           let messages = senderConn.processAfterAuth
           senderConn.processAfterAuth = []
 
-          return messages.reduce((p, m) =>
-            p.then(() => this.computeMessage(m[0], m[1], m[2], m[3], m[4]))
-          , Promise.resolve())
+          messages.forEach(m =>
+            this.computeMessage(m[0], m[1], m[2], m[3], m[4])
+          )
         })
       }
     }
-    if (skipAuth || senderConn.auth != null) {
-      return this.computeMessage(messageType, senderConn, decoder, encoder, sender, skipAuth)
+    if ((skipAuth || senderConn.auth != null) && (messageType !== 'update' || senderConn.isSynced)) {
+      this.computeMessage(messageType, senderConn, decoder, encoder, sender, skipAuth)
     } else {
-      senderConn.processAfterAuth.push([messageType, senderConn, decoder, encoder, sender, false])
+      senderConn.processAfterSync.push([messageType, senderConn, decoder, encoder, sender, false])
     }
   }
 
@@ -270,9 +269,15 @@ export default class AbstractConnector {
 
   _setSyncedWith (user) {
     if (user != null) {
-      this.connections.get(user).isSynced = true
+      const userConn = this.connections.get(user)
+      userConn.isSynced = true
+      const messages = userConn.processAfterSync
+      userConn.processAfterSync = []
+      messages.forEach(m => {
+        this.computeMessage(m[0], m[1], m[2], m[3], m[4])
+      })
     }
-    let conns = Array.from(this.connections.values())
+    const conns = Array.from(this.connections.values())
     if (conns.length > 0 && conns.every(u => u.isSynced)) {
       this._fireIsSyncedListeners()
     }
diff --git a/src/MessageHandler/integrateRemoteStructs.js b/src/MessageHandler/integrateRemoteStructs.js
index 074c6b3b..8f6a7df8 100644
--- a/src/MessageHandler/integrateRemoteStructs.js
+++ b/src/MessageHandler/integrateRemoteStructs.js
@@ -19,22 +19,27 @@ class MissingEntry {
 function _integrateRemoteStructHelper (y, struct) {
   struct._integrate(y)
   if (struct.constructor !== Delete) {
-    let msu = y._missingStructs.get(struct._id.user)
+    const id = struct._id
+    let msu = y._missingStructs.get(id.user)
     if (msu != null) {
-      let len = struct._length
-      for (let i = 0; i < len; i++) {
-        if (msu.has(struct._id.clock + i)) {
-          let msuc = msu.get(struct._id.clock + i)
-          msuc.forEach(missingDef => {
+      let clock = id.clock
+      const finalClock = clock + struct._length
+      for (;clock < finalClock; clock++) {
+        const missingStructs = msu.get(clock)
+        if (missingStructs !== undefined) {
+          missingStructs.forEach(missingDef => {
             missingDef.missing--
             if (missingDef.missing === 0) {
-              let missing = missingDef.struct._fromBinary(y, missingDef.decoder)
+              const decoder = missingDef.decoder
+              let oldPos = decoder.pos
+              let missing = missingDef.struct._fromBinary(y, decoder)
+              decoder.pos = oldPos
               if (missing.length === 0) {
                 y._readyToIntegrate.push(missingDef.struct)
               }
             }
           })
-          msu.delete(struct._id.clock)
+          msu.delete(clock)
         }
       }
     }
@@ -57,10 +62,10 @@ export function stringifyStructs (y, decoder, strBuilder) {
 
 export function integrateRemoteStructs (decoder, encoder, y) {
   while (decoder.length !== decoder.pos) {
-    let decoderPos = decoder.pos
     let reference = decoder.readVarUint()
     let Constr = getStruct(reference)
     let struct = new Constr()
+    let decoderPos = decoder.pos
     let missing = struct._fromBinary(y, decoder)
     if (missing.length === 0) {
       while (struct != null) {
diff --git a/src/Struct/Item.js b/src/Struct/Item.js
index c7ceffed..8b88f96b 100644
--- a/src/Struct/Item.js
+++ b/src/Struct/Item.js
@@ -16,11 +16,27 @@ export function splitHelper (y, a, b, diff) {
   b._id = new ID(aID.user, aID.clock + diff)
   b._origin = a
   b._left = a
+  b._right = a._right
+  if (b._right !== null) {
+    b._right._left = b
+  }
+  b._right_origin = a._right_origin
+  // do not set a._right_origin, as this will lead to problems when syncing
   a._right = b
-  a._right_origin = b
   b._parent = a._parent
   b._parentSub = a._parentSub
   b._deleted = a._deleted
+  // now search all relevant items to the right and update origin
+  // if origin is not it foundOrigins, we don't have to search any longer
+  let foundOrigins = new Set()
+  foundOrigins.add(a)
+  let o = b._right
+  while (o !== null && foundOrigins.has(o._origin)) {
+    if (o._origin === a) {
+      o._origin = b
+    }
+    o = o._right
+  }
   y.os.put(b)
 }
 
@@ -133,21 +149,25 @@ export default class Item {
     // Note that conflictingItems is a subset of itemsBeforeOrigin
     while (o !== null && o !== this._right) {
       itemsBeforeOrigin.add(o)
+      conflictingItems.add(o)
       if (this._origin === o._origin) {
         // case 1
         if (o._id.user < this._id.user) {
           this._left = o
-          conflictingItems = new Set()
+          conflictingItems.clear()
         }
-      } else if (itemsBeforeOrigin.has(o)) {
+      } else if (itemsBeforeOrigin.has(o._origin)) {
         // case 2
-        if (conflictingItems.has(o)) {
+        if (!conflictingItems.has(o._origin)) {
           this._left = o
-          conflictingItems = new Set()
+          conflictingItems.clear()
         }
       } else {
         break
       }
+      // TODO: try to use right_origin instead.
+      // Then you could basically omit conflictingItems!
+      // Note: you probably can't use right_origin in every case.. only when setting _left
       o = o._right
     }
     // reconnect left/right + update parent map/start if necessary
@@ -193,9 +213,12 @@ export default class Item {
     if (this._origin !== null) {
       info += 0b1 // origin is defined
     }
+    // TODO: remove
+    /* no longer send _left
     if (this._left !== this._origin) {
       info += 0b10 // do not copy origin to left
     }
+    */
     if (this._right_origin !== null) {
       info += 0b100
     }
@@ -236,24 +259,9 @@ export default class Item {
           missing.push(originID)
         } else {
           this._origin = origin
-        }
-      }
-    }
-    // read left
-    if (info & 0b10) {
-      // left !== origin
-      const leftID = decoder.readID()
-      if (this._left === null) {
-        const left = y.os.getItemCleanEnd(leftID)
-        if (left === null) {
-          // use origin instead
           this._left = this._origin
-        } else {
-          this._left = left
         }
       }
-    } else {
-      this._left = this._origin
     }
     // read right
     if (info & 0b100) {
diff --git a/src/Struct/ItemJSON.js b/src/Struct/ItemJSON.js
index f17b9bae..3c5fba14 100644
--- a/src/Struct/ItemJSON.js
+++ b/src/Struct/ItemJSON.js
@@ -28,7 +28,9 @@ export default class ItemJSON extends Item {
     }
   }
   _logString () {
-    return `ItemJSON(id:${logID(this._id)},content:${JSON.stringify(this._content)},left:${logID(this._left)},origin:${logID(this._origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `ItemJSON(id:${logID(this._id)},content:${JSON.stringify(this._content)},left:${logID(left)},origin:${logID(origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
   }
   _splitAt (y, diff) {
     if (diff === 0) {
diff --git a/src/Struct/ItemString.js b/src/Struct/ItemString.js
index eaa504f8..3409ae42 100644
--- a/src/Struct/ItemString.js
+++ b/src/Struct/ItemString.js
@@ -19,7 +19,9 @@ export default class ItemString extends Item {
     encoder.writeVarString(this._content)
   }
   _logString () {
-    return `ItemJSON(id:${logID(this._id)},content:${JSON.stringify(this._content)},left:${logID(this._left)},origin:${logID(this._origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `ItemJSON(id:${logID(this._id)},content:${JSON.stringify(this._content)},left:${logID(left)},origin:${logID(origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
   }
   _splitAt (y, diff) {
     if (diff === 0) {
diff --git a/src/Type/YArray.js b/src/Type/YArray.js
index 8673d117..49ef0d79 100644
--- a/src/Type/YArray.js
+++ b/src/Type/YArray.js
@@ -204,6 +204,8 @@ export default class YArray extends Type {
     this.insertAfter(left, content)
   }
   _logString () {
-    return `YArray(id:${logID(this._id)},start:${logID(this._start)},left:${logID(this._left)},origin:${logID(this._origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `YArray(id:${logID(this._id)},start:${logID(this._start)},left:${logID(left)},origin:${logID(origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
   }
 }
diff --git a/src/Type/YMap.js b/src/Type/YMap.js
index 473f04ff..1c7b5fdd 100644
--- a/src/Type/YMap.js
+++ b/src/Type/YMap.js
@@ -83,6 +83,8 @@ export default class YMap extends Type {
     }
   }
   _logString () {
-    return `YMap(id:${logID(this._id)},mapSize:${this._map.size},left:${logID(this._left)},origin:${logID(this._origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `YMap(id:${logID(this._id)},mapSize:${this._map.size},left:${logID(left)},origin:${logID(origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
   }
 }
diff --git a/src/Type/YText.js b/src/Type/YText.js
index 86f1951f..f1ac0414 100644
--- a/src/Type/YText.js
+++ b/src/Type/YText.js
@@ -52,6 +52,8 @@ export default class YText extends YArray {
     })
   }
   _logString () {
-    return `YText(id:${logID(this._id)},start:${logID(this._start)},left:${logID(this._left)},origin:${logID(this._origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `YText(id:${logID(this._id)},start:${logID(this._start)},left:${logID(left)},origin:${logID(origin)},right:${logID(this._right)},parent:${logID(this._parent)},parentSub:${logID(this._parentSub)})`
   }
 }
diff --git a/src/Type/y-xml/YXmlFragment.js b/src/Type/y-xml/YXmlFragment.js
index a86823a1..c3cfcd1a 100644
--- a/src/Type/y-xml/YXmlFragment.js
+++ b/src/Type/y-xml/YXmlFragment.js
@@ -153,6 +153,8 @@ export default class YXmlFragment extends YArray {
     }
   }
   _logString () {
-    return `YXml(id:${logID(this._id)},parent:${logID(this._parent)},parentSub:${this._parentSub})`
+    const left = this._left !== null ? this._left._lastId : null
+    const origin = this._origin !== null ? this._origin._lastId : null
+    return `YXml(id:${logID(this._id)},left:${logID(left)},origin:${logID(origin)},right:${this._right},parent:${logID(this._parent)},parentSub:${this._parentSub})`
   }
 }
diff --git a/test/y-array.tests.js b/test/y-array.tests.js
index ec285913..a32c5a80 100644
--- a/test/y-array.tests.js
+++ b/test/y-array.tests.js
@@ -272,7 +272,7 @@ var arrayTransactions = [
 ]
 
 test('y-array: Random tests (5)', async function randomArray5 (t) {
-  await applyRandomTests(t, arrayTransactions, 5)
+  await applyRandomTests(t, arrayTransactions, 12)
 })
 
 test('y-array: Random tests (42)', async function randomArray42 (t) {
diff --git a/tests-lib/helper.js b/tests-lib/helper.js
index ebf7fe9a..15f536e8 100644
--- a/tests-lib/helper.js
+++ b/tests-lib/helper.js
@@ -248,6 +248,8 @@ export function wait (t) {
 
 export async function applyRandomTests (t, mods, iterations) {
   const chance = new Chance(t.getSeed() * 1000000000)
+    // TODO: remove
+    console.info('seed: ' + t._seed)
   var initInformation = await initArrays(t, { users: 5, chance: chance })
   let { users } = initInformation
   for (var i = 0; i < iterations; i++) {
diff --git a/tests-lib/test-connector.js b/tests-lib/test-connector.js
index 335d4182..8461b1b6 100644
--- a/tests-lib/test-connector.js
+++ b/tests-lib/test-connector.js
@@ -119,22 +119,20 @@ export default function extendTestConnector (Y) {
       })
     }
     receiveMessage (sender, m) {
-      setTimeout(() => {
-        if (this.y.userID !== sender && this.connections.has(sender)) {
-          var buffer = this.connections.get(sender).buffer
-          if (buffer == null) {
-            buffer = this.connections.get(sender).buffer = []
-          }
-          buffer.push(m)
-          if (this.chance.bool({likelihood: 30})) {
-            // flush 1/2 with 30% chance
-            var flushLength = Math.round(buffer.length / 2)
-            buffer.splice(0, flushLength).forEach(m => {
-              super.receiveMessage(sender, m)
-            })
-          }
+      if (this.y.userID !== sender && this.connections.has(sender)) {
+        var buffer = this.connections.get(sender).buffer
+        if (buffer == null) {
+          buffer = this.connections.get(sender).buffer = []
         }
-      }, 0)
+        buffer.push(m)
+        if (this.chance.bool({likelihood: 30})) {
+          // flush 1/2 with 30% chance
+          var flushLength = Math.round(buffer.length / 2)
+          buffer.splice(0, flushLength).forEach(m => {
+            super.receiveMessage(sender, m)
+          })
+        }
+      }
     }
     async _flushAll (flushUsers) {
       if (flushUsers.some(u => u.connector.y.userID === this.y.userID)) {