--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.test/src/org/graalvm/compiler/replacements/test/classfile/ClassfileBytecodeProviderTest.java	Tue Apr 23 14:09:54 2019 -0400
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements.test/src/org/graalvm/compiler/replacements/test/classfile/ClassfileBytecodeProviderTest.java	Tue Apr 23 22:55:09 2019 +0200
@@ -140,6 +140,11 @@
         return false;
     }
 
+    /**
+     * Keep test time down by only sampling a limited number of class files per jar.
+     */
+    private static final int CLASSES_PER_JAR = 250;
+
     @Test
     public void test() {
         RuntimeProvider rt = Graal.getRequiredCapability(RuntimeProvider.class);
@@ -156,28 +161,33 @@
             if (shouldProcess(path)) {
                 try {
                     final ZipFile zipFile = new ZipFile(new File(path));
+                    int index = 0;
+                    int step = zipFile.size() > CLASSES_PER_JAR ? zipFile.size() / CLASSES_PER_JAR : 1;
                     for (final Enumeration<? extends ZipEntry> entry = zipFile.entries(); entry.hasMoreElements();) {
                         final ZipEntry zipEntry = entry.nextElement();
-                        String name = zipEntry.getName();
-                        if (name.endsWith(".class") && !name.equals("module-info.class") && !name.startsWith("META-INF/versions/")) {
-                            String className = name.substring(0, name.length() - ".class".length()).replace('/', '.');
-                            if (isInNativeImage(className)) {
-                                /*
-                                 * Native image requires non-graalsdk classes to be present in the
-                                 * classpath.
-                                 */
-                                continue;
-                            }
-                            if (isGSON(className)) {
-                                /* uses old class format */
-                                continue;
-                            }
-                            try {
-                                checkClass(metaAccess, getSnippetReflection(), className);
-                            } catch (ClassNotFoundException e) {
-                                throw new AssertionError(e);
+                        if ((index % step) == 0) {
+                            String name = zipEntry.getName();
+                            if (name.endsWith(".class") && !name.equals("module-info.class") && !name.startsWith("META-INF/versions/")) {
+                                String className = name.substring(0, name.length() - ".class".length()).replace('/', '.');
+                                if (isInNativeImage(className)) {
+                                    /*
+                                     * Native image requires non-graalsdk classes to be present in
+                                     * the classpath.
+                                     */
+                                    continue;
+                                }
+                                if (isGSON(className)) {
+                                    /* uses old class format */
+                                    continue;
+                                }
+                                try {
+                                    checkClass(metaAccess, getSnippetReflection(), className);
+                                } catch (ClassNotFoundException e) {
+                                    throw new AssertionError(e);
+                                }
                             }
                         }
+                        index++;
                     }
                 } catch (IOException ex) {
                     Assert.fail(ex.toString());