diff --git a/build.xml b/build.xml
index d08656a..31f62d8 100644
--- a/build.xml
+++ b/build.xml
@@ -20,6 +20,8 @@
     <target name="run" description="execution" depends="compile">
         <java classname="lsystem.Main" fork="true">
             <jvmarg value="-ea"/>
+            <jvmarg value="-XX:+UseG1GC"/>
+            <jvmarg value="-XX:+ParallelRefProcEnabled"/>
             <classpath refid="project.classpath"/>
         </java>
     </target>
diff --git a/src/lsystem/engine/Parser.java b/src/lsystem/engine/Parser.java
index ccfbd16..d0987ae 100644
--- a/src/lsystem/engine/Parser.java
+++ b/src/lsystem/engine/Parser.java
@@ -79,7 +79,7 @@ public class Parser {
 	}
     
     /**
-     * Used by {@link Rewrite#rewrite()}
+     * Used by {@link Rewrite#rewrite(String, List, int)} )}
      * @return a list of rules with the left and right sides separated by a {@link lsystem.utils.Pair Pair}
      */
     public List<Pair<String, String>> parseRules() {
diff --git a/src/lsystem/engine/Rewrite.java b/src/lsystem/engine/Rewrite.java
index 81c8b43..3a2253a 100644
--- a/src/lsystem/engine/Rewrite.java
+++ b/src/lsystem/engine/Rewrite.java
@@ -6,18 +6,8 @@ import java.util.List;
 
 public class Rewrite {
 
-    private final String axiom;
-    private final List<Pair<String, String >> rules;
-    private final int recurrences;
 
-    public Rewrite(String axiom, List<Pair<String, String>> rules, int recurrences) {
-        this.axiom = axiom;
-        this.rules = rules;
-        this.recurrences = recurrences;
-    }
-
-
-    private String replaceRulesByID(final String rewritten) {
+    private static String replaceRulesByID(final String rewritten, List<Pair<String, String>> rules) {
         String toRewrite = rewritten;
         for(int j = 0; j < rules.size(); ++j){
             Pair<String, String> pair = rules.get(j);
@@ -26,7 +16,7 @@ public class Rewrite {
         return toRewrite;
     }
 
-    private String replaceIDByRuleApplication(final String toRewrite) {
+    private static String replaceIDByRuleApplication(final String toRewrite, List<Pair<String, String>> rules) {
         String rewritten = toRewrite;
         for(int j = 0; j < rules.size(); ++j){
             rewritten = rewritten.replace("${" + j + "}", rules.get(j).getRight());
@@ -34,11 +24,12 @@ public class Rewrite {
         return rewritten;
     }
 
-    public String rewrite() {
+    public static String rewrite(String axiom, List<Pair<String, String>> rules, int recurrences) {
         String rewritten = axiom;
         for(int i = 0; i < recurrences; ++i) {
-            String toRewrite = replaceRulesByID(rewritten);
-            rewritten = replaceIDByRuleApplication(toRewrite);
+            String toRewrite = replaceRulesByID(rewritten, rules);
+            rewritten = replaceIDByRuleApplication(toRewrite, rules);
+            System.out.println(i + " / " + recurrences + " : " + rewritten.length());
         }
         return rewritten.replace("[", "Y[");
     }
diff --git a/src/lsystem/screen/AbstractCanvas.java b/src/lsystem/screen/AbstractCanvas.java
index da7fd69..0540ef9 100644
--- a/src/lsystem/screen/AbstractCanvas.java
+++ b/src/lsystem/screen/AbstractCanvas.java
@@ -36,6 +36,7 @@ public abstract class AbstractCanvas {
             @Override
             public void windowClosing(WindowEvent e) {
                 frame.dispose();
+                setVisible(false);
             }
         });
         frame.getContentPane().add(glCanvas, BorderLayout.CENTER);
diff --git a/src/lsystem/screen/main/Listener.java b/src/lsystem/screen/main/Listener.java
index 3fa6219..7fe7948 100644
--- a/src/lsystem/screen/main/Listener.java
+++ b/src/lsystem/screen/main/Listener.java
@@ -1,6 +1,5 @@
 package lsystem.screen.main;
 
-import lsystem.engine.Element;
 import lsystem.engine.Parser;
 import lsystem.engine.Rewrite;
 import lsystem.screen.gl3d.GLCanvas;
@@ -53,14 +52,14 @@ public class Listener implements ActionListener, KeyListener {
                     JOptionPane.showMessageDialog(null, "Vos règles ou votre axiome ne sont pas correctement écrites, veuillez recommencer");
                     new Listener(null, index, "Clear",tab);
                 } else {
-                    new Thread(() -> {
-                        Rewrite rewriter = new Rewrite(axiom, parser.parseRules(), tab.getNbIterations());
-                        final String word = rewriter.rewrite();
-                        System.out.println(word);
-                        final Element parsed = Parser.parse(word);
-                        GLCanvas canvas = new GLCanvas(parsed);
+                    Thread thread = new Thread(() -> {
+                        GLCanvas canvas = new GLCanvas(
+                                Parser.parse(Rewrite.rewrite(axiom, parser.parseRules(), tab.getNbIterations()))
+                        );
                         canvas.setVisible(true);
-                    }).start();
+                    });
+                    thread.setDaemon(true);
+                    thread.start();
                 }
                 break;
 
diff --git a/src/lsystem/screen/main/Tab.java b/src/lsystem/screen/main/Tab.java
index 6c62f09..2c9f9df 100644
--- a/src/lsystem/screen/main/Tab.java
+++ b/src/lsystem/screen/main/Tab.java
@@ -29,7 +29,7 @@ public class Tab extends JPanel{
         nbIterations.setModel(new SpinnerNumberModel(1, 1, 15, 1));
 
         JLabel itLabel  = new JLabel("Nombre d'itérations : ");
-        itSpinner = new JSpinner(new SpinnerNumberModel(1, 1, 15, 1));
+        itSpinner = new JSpinner(new SpinnerNumberModel(1, 1, 30, 1));
         ((JSpinner.DefaultEditor) itSpinner.getEditor()).getTextField().setEditable(false);
 
         JLabel axiome = new JLabel("Axiome :");
@@ -74,7 +74,7 @@ public class Tab extends JPanel{
 
         tabs.addTab("Génération"+String.valueOf(nbTabs), tab);
     }
-    public JTextArea textArea(String texte,int nb){
+    public JTextArea textArea(String texte, int nb){
         JTextArea res = new JTextArea();
         res.setText(texte);
         res.setEditable(false);