diff --git a/test/hotspot/jtreg/gc/shenandoah/generational/TestOldGrowthTriggers.java b/test/hotspot/jtreg/gc/shenandoah/generational/TestOldGrowthTriggers.java
index 7af81fabe13..2af784fd034 100644
--- a/test/hotspot/jtreg/gc/shenandoah/generational/TestOldGrowthTriggers.java
+++ b/test/hotspot/jtreg/gc/shenandoah/generational/TestOldGrowthTriggers.java
@@ -1,5 +1,6 @@
 /*
  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,15 +26,14 @@
 /*
  * @test id=generational
  * @summary Test that growth of old-gen triggers old-gen marking
- * @key intermittent
  * @requires vm.gc.Shenandoah
  * @requires vm.flagless
  * @library /test/lib
  * @run driver TestOldGrowthTriggers
  */
 
-import java.util.*;
-import java.math.BigInteger;
+import java.util.Arrays;
+import java.util.BitSet;
 
 import jdk.test.lib.process.ProcessTools;
 import jdk.test.lib.process.OutputAnalyzer;
@@ -41,36 +41,40 @@ import jdk.test.lib.process.OutputAnalyzer;
 public class TestOldGrowthTriggers {
 
     public static void makeOldAllocations() {
-        // Expect most of the BigInteger entries placed into array to be promoted, and most will eventually become garbage within old
+        // Expect most of the BitSet entries placed into array to be promoted, and most will eventually become garbage within old
 
-        final int ArraySize = 512 * 1024;   // 512K entries
-        final int BitsInBigInteger = 128;
-        final int RefillIterations = 64;
-        BigInteger array[] = new BigInteger[ArraySize];
-        Random r = new Random(46);
+        final int ArraySize = 1024;  // 1K entries
+        final int RefillIterations = 128;
+        BitSet[] array = new BitSet[ArraySize];
 
         for (int i = 0; i < ArraySize; i++) {
-            array[i] = new BigInteger(BitsInBigInteger, r);
+            array[i] = new BitSet(256 * 1024);
         }
 
         for (int refillCount = 0; refillCount < RefillIterations; refillCount++) {
-            // Each refill repopulates ArraySize randomly selected elements within array
-            for (int i = 0; i < ArraySize; i++) {
-                int replaceIndex = r.nextInt(ArraySize);
-                int deriveIndex = r.nextInt(ArraySize);
+            // Each refill repopulates ArraySize
+            for (int i = 1; i < ArraySize; i++) {
+                int replaceIndex = i;
+                int deriveIndex = i-1;
+
                 switch (i & 0x7) {
-                    case 0,1,2:
-                        // creates new old BigInteger, releases old BigInteger,
-                        // may create ephemeral data while computing gcd
-                        array[replaceIndex] = array[replaceIndex].gcd(array[deriveIndex]);
-                        break;
-                    case 3,4:
-                        // creates new old BigInteger, releases old BigInteger
-                        array[replaceIndex] = array[replaceIndex].multiply(array[deriveIndex]);
-                        break;
-                    case 5,6,7:
+                    case 0,1,2 -> {
+                        // creates new BitSet, releases old BitSet,
+                        // create ephemeral data while computing
+                        BitSet result = (BitSet) array[deriveIndex].clone();
+                        for (int j=0; j<10; j++) {
+                            result = (BitSet) array[deriveIndex].clone();
+                        }
+                        array[replaceIndex] = result;
+                    }
+                    case 3,4 -> {
+                        // creates new BitSet, releases old BitSet
+                        BitSet result = (BitSet) array[deriveIndex].clone();
+                        array[replaceIndex] = result;
+                    }
+                    case 5,6,7 -> {
                         // do nothing, let all objects in the array age to increase pressure on old generation
-                        break;
+                    }
                 }
             }
         }
@@ -93,6 +97,8 @@ public class TestOldGrowthTriggers {
         }
 
         testOld("-Xlog:gc",
+                "-XX:ConcGCThreads=1",
+                "-XX:ParallelGCThreads=1",
                 "-Xms96m",
                 "-Xmx96m",
                 "-XX:+UnlockDiagnosticVMOptions",
@@ -108,6 +114,8 @@ public class TestOldGrowthTriggers {
         );
 
         testOld("-Xlog:gc",
+                "-XX:ConcGCThreads=1",
+                "-XX:ParallelGCThreads=1",
                 "-Xms96m",
                 "-Xmx96m",
                 "-XX:+UnlockDiagnosticVMOptions",