diff --git a/source/de/anomic/crawler/Balancer.java b/source/de/anomic/crawler/Balancer.java
index 69aed1e2a..a9956196e 100644
--- a/source/de/anomic/crawler/Balancer.java
+++ b/source/de/anomic/crawler/Balancer.java
@@ -230,12 +230,7 @@ public class Balancer {
     }
     
     public synchronized boolean has(String urlhash) {
-        try {
-            return urlFileIndex.has(urlhash.getBytes());
-        } catch (IOException e) {
-            e.printStackTrace();
-            return false;
-        }
+        return urlFileIndex.has(urlhash.getBytes());
     }
     
     public boolean notEmpty() {
@@ -345,7 +340,7 @@ public class Balancer {
         urlFileIndex.put(entry.toRow());
         
         // check size of domainStacks and flush
-        if ((domainStacks.size() > 20) || (sizeDomainStacks() > 1000)) {
+        if ((domainStacks.size() > 100) || (sizeDomainStacks() > 1000)) {
             flushOnceDomStacks(1, urlRAMStack.size() < 100); // when the ram stack is small, flush it there
         }
     }
diff --git a/source/de/anomic/crawler/CrawlStacker.java b/source/de/anomic/crawler/CrawlStacker.java
index ba2ea7c49..fa0a4c05d 100644
--- a/source/de/anomic/crawler/CrawlStacker.java
+++ b/source/de/anomic/crawler/CrawlStacker.java
@@ -238,6 +238,11 @@ public final class CrawlStacker extends Thread {
             int currentdepth, 
             CrawlProfile.entry profile) {
         if (profile == null) return;
+        
+        // check first before we create a big object
+        if (this.urlEntryCache.has(nexturl.hash().getBytes())) return;
+
+        // now create the big object before we enter the synchronized block
         CrawlEntry newEntry = new CrawlEntry(
                     initiatorHash,
                     nexturl,
@@ -249,15 +254,15 @@ public final class CrawlStacker extends Thread {
                     0,
                     0
                     );
-
         if (newEntry == null) return;
+        kelondroRow.Entry newEntryRow = newEntry.toRow();
                 
-        synchronized(this.urlEntryHashCache) {                    
+        synchronized(this.urlEntryHashCache) {
             kelondroRow.Entry oldValue;
             boolean hostknown = true;
             if (prequeue) hostknown = prefetchHost(nexturl.getHost());
             try {
-                oldValue = this.urlEntryCache.put(newEntry.toRow());
+                oldValue = this.urlEntryCache.put(newEntryRow);
             } catch (IOException e) {
                 oldValue = null;
             }                        
@@ -346,7 +351,7 @@ public final class CrawlStacker extends Thread {
         synchronized (this.urlEntryHashCache) {
             urlHash = this.urlEntryHashCache.removeFirst();
             if (urlHash == null) throw new IOException("urlHash is null");
-            entry = this.urlEntryCache.remove(urlHash.getBytes(), false);
+            entry = this.urlEntryCache.remove(urlHash.getBytes(), true);
         }
 
         if ((urlHash == null) || (entry == null)) return null;
diff --git a/source/de/anomic/crawler/ResultURLs.java b/source/de/anomic/crawler/ResultURLs.java
index 45bec1286..7072ff126 100644
--- a/source/de/anomic/crawler/ResultURLs.java
+++ b/source/de/anomic/crawler/ResultURLs.java
@@ -90,15 +90,6 @@ public final class ResultURLs {
         assert executorHash != null;
         if (e == null) { return; }
         try {
-//            switch (stackType) {
-//                case 0: break;
-//                case 1: externResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//                case 2: searchResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//                case 3: transfResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//                case 4: proxyResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//                case 5: lcrawlResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//                case 6: gcrawlResultStack.add(e.hash() + initiatorHash + executorHash); break;
-//            }
             final List<String> resultStack = getStack(stackType);
             if(resultStack != null) {
                 resultStack.add(e.hash() + initiatorHash + executorHash);
@@ -121,54 +112,18 @@ public final class ResultURLs {
         } else {
             return -1;
         }
-//        switch (stack) {
-//            case 1: return externResultStack.size();
-//            case 2: return searchResultStack.size();
-//            case 3: return transfResultStack.size();
-//            case 4: return proxyResultStack.size();
-//            case 5: return lcrawlResultStack.size();
-//            case 6: return gcrawlResultStack.size();
-//        }
-//        return -1;
     }
 
     public synchronized String getUrlHash(int stack, int pos) {
         return getHashNo(stack, pos, 0);
-//        switch (stack) {
-//            case 1: return (externResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//            case 2: return (searchResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//            case 3: return (transfResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//            case 4: return (proxyResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//            case 5: return (lcrawlResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//            case 6: return (gcrawlResultStack.get(pos)).substring(0, yacySeedDB.commonHashLength);
-//        }
-//        return null;
     }
 
     public synchronized String getInitiatorHash(int stack, int pos) {
         return getHashNo(stack, pos, 1);
-//        switch (stack) {
-//            case 1: return (externResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//            case 2: return (searchResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//            case 3: return (transfResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//            case 4: return (proxyResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//            case 5: return (lcrawlResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//            case 6: return (gcrawlResultStack.get(pos)).substring(yacySeedDB.commonHashLength, yacySeedDB.commonHashLength * 2);
-//        }
-//        return null;
     }
 
     public synchronized String getExecutorHash(final int stack, int pos) {
         return getHashNo(stack, pos, 2);
-//      switch (stack) {
-//      case 1: return (externResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//      case 2: return (searchResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//      case 3: return (transfResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//      case 4: return (proxyResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//      case 5: return (lcrawlResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//      case 6: return (gcrawlResultStack.get(pos)).substring(yacySeedDB.commonHashLength * 2, yacySeedDB.commonHashLength * 3);
-//  }
-//  return null;
     }
     
     /**
@@ -221,6 +176,7 @@ public final class ResultURLs {
         
         final List<String> resultStack = getStack(stack);
         if(resultStack != null) {
+            assert pos < resultStack.size() : "pos = " + pos + ", resultStack.size() = " + resultStack.size();
             if(pos < resultStack.size()) {
                 return resultStack.get(pos);
             } else {
diff --git a/source/de/anomic/crawler/ZURL.java b/source/de/anomic/crawler/ZURL.java
index 1821fa34d..41303cc39 100755
--- a/source/de/anomic/crawler/ZURL.java
+++ b/source/de/anomic/crawler/ZURL.java
@@ -141,11 +141,7 @@ public class ZURL {
     }
 
     public boolean exists(String urlHash) {
-        try {
-            return urlIndex.has(urlHash.getBytes());
-        } catch (IOException e) {
-            return false;
-        }
+        return urlIndex.has(urlHash.getBytes());
     }
     
     public void clearStack() {
diff --git a/source/de/anomic/index/indexRAMRI.java b/source/de/anomic/index/indexRAMRI.java
index 8a56dc598..5ee381aeb 100644
--- a/source/de/anomic/index/indexRAMRI.java
+++ b/source/de/anomic/index/indexRAMRI.java
@@ -28,6 +28,7 @@ package de.anomic.index;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Set;
 
 import de.anomic.kelondro.kelondroCloneableIterator;
@@ -159,7 +160,7 @@ public final class indexRAMRI implements indexRI, indexRIReader {
         return null;
     }
     
-    public synchronized String bestFlushWordHash() {
+    private String bestFlushWordHash() {
         // select appropriate hash
         // we have 2 different methods to find a good hash:
         // - the oldest entry in the cache
@@ -189,7 +190,8 @@ public final class indexRAMRI implements indexRI, indexRIReader {
                 hash = hashDate.getMinObject(); // flush oldest entries
             }
             if (hash == null) {
-                heap.wordContainers(null, false).next();
+                indexContainer ic = heap.wordContainers(null, false).next();
+                if (ic != null) hash = ic.getWordHash();
             }
             return hash;
         } catch (Exception e) {
@@ -198,6 +200,23 @@ public final class indexRAMRI implements indexRI, indexRIReader {
         return null;
     }
 
+    public synchronized ArrayList<indexContainer> bestFlushContainers(int count) {
+        ArrayList<indexContainer> containerList = new ArrayList<indexContainer>();
+        String hash;
+        indexContainer container;
+        for (int i = 0; i < count; i++) {
+            hash = bestFlushWordHash();
+            if (hash == null) return containerList;
+            container = heap.delete(hash);
+            assert (container != null);
+            if (container == null) return containerList;
+            hashScore.deleteScore(hash);
+            hashDate.deleteScore(hash);
+            containerList.add(container);
+        }
+        return containerList;
+    }
+    
     private int intTime(long longTime) {
         return (int) Math.max(0, ((longTime - initTime) / 1000));
     }
diff --git a/source/de/anomic/index/indexRepositoryReference.java b/source/de/anomic/index/indexRepositoryReference.java
index 3d74aa340..2b56e0dbf 100644
--- a/source/de/anomic/index/indexRepositoryReference.java
+++ b/source/de/anomic/index/indexRepositoryReference.java
@@ -151,11 +151,7 @@ public final class indexRepositoryReference {
 
     public synchronized boolean exists(String urlHash) {
         if (urlIndexFile == null) return false; // case may happen during shutdown
-        try {
-            return urlIndexFile.has(urlHash.getBytes());
-        } catch (IOException e) {
-            return false;
-        }
+        return urlIndexFile.has(urlHash.getBytes());
     }
 
     public kelondroCloneableIterator<indexURLReference> entries(boolean up, String firstHash) throws IOException {
diff --git a/source/de/anomic/kelondro/kelondroBytesIntMap.java b/source/de/anomic/kelondro/kelondroBytesIntMap.java
index d53d2b4db..0c9e28f3d 100644
--- a/source/de/anomic/kelondro/kelondroBytesIntMap.java
+++ b/source/de/anomic/kelondro/kelondroBytesIntMap.java
@@ -49,6 +49,11 @@ public class kelondroBytesIntMap {
         return index.row();
     }
     
+    public synchronized boolean has(byte[] key) {
+        assert (key != null);
+        return index.has(key);
+    }
+    
     public synchronized int geti(byte[] key) throws IOException {
         assert (key != null);
         kelondroRow.Entry indexentry = index.get(key);
diff --git a/source/de/anomic/kelondro/kelondroCache.java b/source/de/anomic/kelondro/kelondroCache.java
index ca8a51a20..6b2ef94fb 100644
--- a/source/de/anomic/kelondro/kelondroCache.java
+++ b/source/de/anomic/kelondro/kelondroCache.java
@@ -191,7 +191,7 @@ public class kelondroCache implements kelondroIndex {
         readMissCache = null;
     }
 
-    public boolean has(byte[] key) throws IOException {
+    public boolean has(byte[] key) {
         // first look into the miss cache
         if (readMissCache != null) {
             if (readMissCache.get(key) != null) {
diff --git a/source/de/anomic/kelondro/kelondroEcoTable.java b/source/de/anomic/kelondro/kelondroEcoTable.java
index c23bd4f60..cd7374e05 100644
--- a/source/de/anomic/kelondro/kelondroEcoTable.java
+++ b/source/de/anomic/kelondro/kelondroEcoTable.java
@@ -345,10 +345,15 @@ public class kelondroEcoTable implements kelondroIndex {
         return rowdef.newEntry(b);
     }
 
-    public synchronized boolean has(byte[] key) throws IOException {
-        assert file.size() == index.size() + fail : "file.size() = " + file.size() + ", index.size() = " + index.size();
+    public synchronized boolean has(byte[] key) {
+        try {
+            assert file.size() == index.size() + fail : "file.size() = " + file.size() + ", index.size() = " + index.size();
+        } catch (IOException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
         assert ((table == null) || (table.size() == index.size()));
-        return index.geti(key) >= 0;
+        return index.has(key);
     }
 
     public synchronized kelondroCloneableIterator<byte[]> keys(boolean up, byte[] firstKey) throws IOException {
diff --git a/source/de/anomic/kelondro/kelondroFlexTable.java b/source/de/anomic/kelondro/kelondroFlexTable.java
index f949dd958..53ad9d18e 100644
--- a/source/de/anomic/kelondro/kelondroFlexTable.java
+++ b/source/de/anomic/kelondro/kelondroFlexTable.java
@@ -147,12 +147,12 @@ public class kelondroFlexTable extends kelondroFlexWidthArray implements kelondr
         return RAMIndex;
     }
     
-    public synchronized boolean has(byte[] key) throws IOException {
+    public synchronized boolean has(byte[] key) {
         // it is not recommended to implement or use a has predicate unless
         // it can be ensured that it causes no IO
         if ((kelondroAbstractRecords.debugmode) && (RAMIndex != true)) serverLog.logWarning("kelondroFlexTable", "RAM index warning in file " + super.tablename);
         assert this.size() == index.size() : "content.size() = " + this.size() + ", index.size() = " + index.size();
-        return index.geti(key) >= 0;
+        return index.has(key);
     }
     
     private kelondroBytesIntMap initializeRamIndex(int initialSpace) {
diff --git a/source/de/anomic/kelondro/kelondroIndex.java b/source/de/anomic/kelondro/kelondroIndex.java
index 4dae69e41..2c04d975f 100644
--- a/source/de/anomic/kelondro/kelondroIndex.java
+++ b/source/de/anomic/kelondro/kelondroIndex.java
@@ -61,7 +61,7 @@ public interface kelondroIndex {
     public int size();
     public kelondroProfile profile();
     public kelondroRow row();
-    public boolean has(byte[] key) throws IOException; // use this only if there is no get in case that has returns true
+    public boolean has(byte[] key); // use this only if there is no get in case that has returns true
     public kelondroRow.Entry get(byte[] key) throws IOException;
     public kelondroRow.Entry put(kelondroRow.Entry row) throws IOException;
     public kelondroRow.Entry put(kelondroRow.Entry row, Date entryDate) throws IOException;
diff --git a/source/de/anomic/kelondro/kelondroRowSet.java b/source/de/anomic/kelondro/kelondroRowSet.java
index 17b8b4617..46efd9303 100644
--- a/source/de/anomic/kelondro/kelondroRowSet.java
+++ b/source/de/anomic/kelondro/kelondroRowSet.java
@@ -109,7 +109,10 @@ public class kelondroRowSet extends kelondroRowCollection implements kelondroInd
 	}
    
     public synchronized boolean has(byte[] key) {
-        return (get(key) != null);
+        long handle = profile.startRead();
+        int index = find(key, 0, key.length);
+        profile.stopRead(handle);
+        return index >= 0;
     }
     
     public synchronized kelondroRow.Entry get(byte[] key) {
diff --git a/source/de/anomic/kelondro/kelondroSQLTable.java b/source/de/anomic/kelondro/kelondroSQLTable.java
index 7559c086c..be0c537a2 100644
--- a/source/de/anomic/kelondro/kelondroSQLTable.java
+++ b/source/de/anomic/kelondro/kelondroSQLTable.java
@@ -135,8 +135,12 @@ public class kelondroSQLTable implements kelondroIndex {
         return this.rowdef;
     }
     
-    public boolean has(byte[] key) throws IOException {
-        return (get(key) != null);
+    public boolean has(byte[] key) {
+        try {
+            return (get(key) != null);
+        } catch (IOException e) {
+            return false;
+        }
     }
     
     public ArrayList<kelondroRowCollection> removeDoubles() {
diff --git a/source/de/anomic/kelondro/kelondroSplitTable.java b/source/de/anomic/kelondro/kelondroSplitTable.java
index dbd4a25c9..72d5c33a3 100644
--- a/source/de/anomic/kelondro/kelondroSplitTable.java
+++ b/source/de/anomic/kelondro/kelondroSplitTable.java
@@ -139,7 +139,7 @@ public class kelondroSplitTable implements kelondroIndex {
                 if (f.isDirectory()) {
                     // this is a kelonodroFlex table
                     serverLog.logInfo("kelondroSplitTable", "opening partial flex table " + path);
-                    table = new kelondroCache(new kelondroFlexTable(path, maxf, rowdef, 0, resetOnFail));
+                    table = new kelondroFlexTable(path, maxf, rowdef, 0, resetOnFail);
                 } else {
                     serverLog.logInfo("kelondroSplitTable", "opening partial eco table " + f);
                     table = new kelondroEcoTable(f, rowdef, kelondroEcoTable.tailCacheUsageAuto, EcoFSBufferSize, 0);
@@ -209,7 +209,7 @@ public class kelondroSplitTable implements kelondroIndex {
         return this.rowdef;
     }
     
-    public boolean has(byte[] key) throws IOException {
+    public boolean has(byte[] key) {
         return keeperOf(key) != null;
     }
     
@@ -276,19 +276,13 @@ public class kelondroSplitTable implements kelondroIndex {
             try {
                 cs.submit(new Callable<kelondroIndex>() {
                     public kelondroIndex call() {
-                        try {
-                            if (table.has(key)) return table; else return dummyIndex;
-                        } catch (IOException e) {
-                            return dummyIndex;
-                        }
+                        if (table.has(key)) return table; else return dummyIndex;
                     }
                 });
             } catch (RejectedExecutionException e) {
                 // the executor is either shutting down or the blocking queue is full
                 // execute the search direct here without concurrency
-                try {
-                    if (table.has(key)) return table;
-                } catch (IOException ee) {}
+                if (table.has(key)) return table;
                 rejected++;
             }
         }
diff --git a/source/de/anomic/kelondro/kelondroTree.java b/source/de/anomic/kelondro/kelondroTree.java
index 3d69bef0e..84607011e 100644
--- a/source/de/anomic/kelondro/kelondroTree.java
+++ b/source/de/anomic/kelondro/kelondroTree.java
@@ -170,7 +170,7 @@ public class kelondroTree extends kelondroCachedRecords implements kelondroIndex
         n.commit();
     }
 
-    public boolean has(byte[] key) throws IOException {
+    public boolean has(byte[] key) {
         throw new UnsupportedOperationException("has should not be used with kelondroTree.");
     }
     
diff --git a/source/de/anomic/plasma/plasmaCondenser.java b/source/de/anomic/plasma/plasmaCondenser.java
index 6f9f7cff0..6f2f7d284 100644
--- a/source/de/anomic/plasma/plasmaCondenser.java
+++ b/source/de/anomic/plasma/plasmaCondenser.java
@@ -358,7 +358,7 @@ public final class plasmaCondenser {
                         k = it.next();
                         wsp = words.get(k);
                         wsp.check(idx);
-                        words.put(k, wsp);
+                        words.put(k, wsp); // is that necessary?
                     }
                 }
                 sentence = new StringBuffer(100);
diff --git a/source/de/anomic/plasma/plasmaWordIndex.java b/source/de/anomic/plasma/plasmaWordIndex.java
index a8e3e3595..7941910ae 100644
--- a/source/de/anomic/plasma/plasmaWordIndex.java
+++ b/source/de/anomic/plasma/plasmaWordIndex.java
@@ -502,19 +502,8 @@ public final class plasmaWordIndex implements indexRI {
             }
         }
         count = count - containerList.size();
-        for (int i = 0; i < count; i++) { // possible position of outOfMemoryError ?
-            synchronized (ram) {
-                if (ram.size() == 0) break;
-                if (serverMemory.available() < collections.minMem()) break; // protect memory during flush
-                
-                // select one word to flush
-                wordHash = ram.bestFlushWordHash();
-                
-                // move one container from ram to flush list
-                if (wordHash == null) c = null; else c = ram.deleteContainer(wordHash);
-            }
-            if (c != null) containerList.add(c);
-        }
+        containerList.addAll(ram.bestFlushContainers(count));
+        
         // flush the containers
         for (indexContainer container : containerList) collections.addEntries(container);
         //System.out.println("DEBUG-Finished flush of " + count + " entries from RAM to DB in " + (System.currentTimeMillis() - start) + " milliseconds");