diff --git a/lib/filterlib.php b/lib/filterlib.php
index 51910de9559..a4a8617e235 100644
--- a/lib/filterlib.php
+++ b/lib/filterlib.php
@@ -81,7 +81,7 @@ class filter_manager {
     public static function instance() {
         global $CFG;
         if (is_null(self::$singletoninstance)) {
-            if (!empty($CFG->perfdebug)) {
+            if (!empty($CFG->perfdebug) and $CFG->perfdebug > 7) {
                 self::$singletoninstance = new performance_measuring_filter_manager();
             } else {
                 self::$singletoninstance = new self();
diff --git a/lib/tests/filter_test.php b/lib/tests/filter_test.php
index 2c0127b3606..41ca6fcd9e1 100644
--- a/lib/tests/filter_test.php
+++ b/lib/tests/filter_test.php
@@ -723,3 +723,22 @@ class filter_filter_set_applies_to_strings extends advanced_testcase {
         $this->assertEquals(1, $CFG->filterall);
     }
 }
+
+
+class filter_manager_testcase extends advanced_testcase {
+    public function test_filter_manager_instance() {
+        $this->resetAfterTest();
+
+        set_config('perfdebug', 7);
+        filter_manager::reset_caches();
+        $filterman = filter_manager::instance();
+        $this->assertInstanceOf('filter_manager', $filterman);
+        $this->assertNotInstanceOf('performance_measuring_filter_manager', $filterman);
+
+        set_config('perfdebug', 15);
+        filter_manager::reset_caches();
+        $filterman = filter_manager::instance();
+        $this->assertInstanceOf('filter_manager', $filterman);
+        $this->assertInstanceOf('performance_measuring_filter_manager', $filterman);
+    }
+}