diff --git a/src/com/jpexs/decompiler/flash/gui/MainPanel.java b/src/com/jpexs/decompiler/flash/gui/MainPanel.java
index 517d64311..e4dab41a0 100644
--- a/src/com/jpexs/decompiler/flash/gui/MainPanel.java
+++ b/src/com/jpexs/decompiler/flash/gui/MainPanel.java
@@ -5050,6 +5050,7 @@ public final class MainPanel extends JPanel implements TreeSelectionListener, Se
 
         public CalculateMissingNeededThread() {
             super("calculateMissingNeededThread");
+            setPriority(Thread.MIN_PRIORITY);
         }
 
         private boolean recalculate = false;