diff --git a/source/net/yacy/cora/protocol/Domains.java b/source/net/yacy/cora/protocol/Domains.java
index f0f687840..10dc7b360 100644
--- a/source/net/yacy/cora/protocol/Domains.java
+++ b/source/net/yacy/cora/protocol/Domains.java
@@ -803,7 +803,7 @@ public class Domains {
         cacheHit_Insert++;
     }
 
-    final private static TimeLimiter timeLimiter = new SimpleTimeLimiter(Executors.newFixedThreadPool(20));
+    final private static TimeLimiter timeLimiter = new SimpleTimeLimiter(Executors.newCachedThreadPool());
 
     /**
      * strip off any parts of an url, address string (containing host/ip:port) or raw IPs/Hosts,
diff --git a/source/net/yacy/cora/protocol/http/HTTPClient.java b/source/net/yacy/cora/protocol/http/HTTPClient.java
index 4082cb486..7f665822d 100644
--- a/source/net/yacy/cora/protocol/http/HTTPClient.java
+++ b/source/net/yacy/cora/protocol/http/HTTPClient.java
@@ -117,7 +117,7 @@ public class HTTPClient {
 	private long upbytes = 0L;
 	private String host = null;
 	private final long timeout;
-	private static ExecutorService executor = Executors.newFixedThreadPool(200);
+	private static ExecutorService executor = Executors.newCachedThreadPool();
 
     public HTTPClient(final ClientIdentification.Agent agent) {
         super();
diff --git a/source/net/yacy/document/importer/MediawikiImporter.java b/source/net/yacy/document/importer/MediawikiImporter.java
index d6f116638..1e9e7a6ef 100644
--- a/source/net/yacy/document/importer/MediawikiImporter.java
+++ b/source/net/yacy/document/importer/MediawikiImporter.java
@@ -175,7 +175,7 @@ public class MediawikiImporter extends Thread implements Importer {
             final int threads = Math.max(2, Runtime.getRuntime().availableProcessors() - 1);
             final BlockingQueue<wikiparserrecord> in = new ArrayBlockingQueue<wikiparserrecord>(threads * 10);
             final BlockingQueue<wikiparserrecord> out = new ArrayBlockingQueue<wikiparserrecord>(threads * 10);
-            final ExecutorService service = Executors.newFixedThreadPool(threads + 1);
+            final ExecutorService service = Executors.newCachedThreadPool();
             final convertConsumer[] consumers = new convertConsumer[threads];
             final Future<?>[] consumerResults = (Future<?>[]) Array.newInstance(Future.class, threads);
             for (int i = 0; i < threads; i++) {
@@ -325,7 +325,7 @@ public class MediawikiImporter extends Thread implements Importer {
         final PositionAwareReader in = new PositionAwareReader(dumpFile);
         final indexProducer producer = new indexProducer(100, idxFromMediawikiXML(dumpFile));
         final wikiConsumer consumer = new wikiConsumer(100, producer);
-        final ExecutorService service = Executors.newFixedThreadPool(2);
+        final ExecutorService service = Executors.newCachedThreadPool();
         final Future<Integer> producerResult = service.submit(consumer);
         final Future<Integer> consumerResult = service.submit(producer);
         service.shutdown();
diff --git a/source/net/yacy/kelondro/blob/ArrayStack.java b/source/net/yacy/kelondro/blob/ArrayStack.java
index 2e3d8b3b5..bf2e1d781 100644
--- a/source/net/yacy/kelondro/blob/ArrayStack.java
+++ b/source/net/yacy/kelondro/blob/ArrayStack.java
@@ -879,7 +879,7 @@ public class ArrayStack implements BLOB {
         assert mem() <= m : "m = " + m + ", mem() = " + mem();
     }
 
-    private static final ExecutorService DELETE_EXECUTOR = Executors.newFixedThreadPool(128);
+    private static final ExecutorService DELETE_EXECUTOR = Executors.newCachedThreadPool();
 
     /**
      * close the BLOB