diff --git a/lib/core/constants.js b/lib/core/constants.js
index 71918e37..c5b9fd2b 100644
--- a/lib/core/constants.js
+++ b/lib/core/constants.js
@@ -27,7 +27,10 @@ const definitions = [
 
 const constants = {
   helpUrlBase: 'https://dequeuniversity.com/rules/',
+  // Size of a grid square in pixels
   gridSize: 200,
+  // At a certain point, looping over an array of elements and using .match on them
+  // is slower than just running querySelectorAll again.
   selectorSimilarFilterLimit: 700,
   results: [],
   resultGroups: [],
@@ -44,7 +47,15 @@ const constants = {
     timeout: 10000
   }),
   allOrigins: '<unsafe_all_origins>',
-  sameOrigin: '<same_origin>'
+  sameOrigin: '<same_origin>',
+  serializableErrorProps: Object.freeze([
+    'message',
+    'stack',
+    'name',
+    'code',
+    'ruleId',
+    'method'
+  ])
 };
 
 definitions.forEach(definition => {
diff --git a/lib/core/utils/performance-timer.js b/lib/core/utils/performance-timer.js
index 5b26c858..1ee71a2b 100644
--- a/lib/core/utils/performance-timer.js
+++ b/lib/core/utils/performance-timer.js
@@ -73,17 +73,27 @@ const performanceTimer = (() => {
      * @param {String} endMark String name of mark to end measuring
      */
     measure(measureName, startMark, endMark, details = {}) {
-      if (window.performance && window.performance.measure !== undefined) {
-        if (Object.keys(details).length > 0) {
-          const measureOpts = {
-            detail: details,
-            start: startMark,
-            end: endMark
-          };
-          window.performance.measure(measureName, measureOpts);
-        } else {
-          window.performance.measure(measureName, startMark, endMark);
+      try {
+        if (window.performance && window.performance.measure !== undefined) {
+          if (Object.keys(details).length > 0) {
+            const measureOpts = {
+              detail: details,
+              start: startMark,
+              end: endMark
+            };
+            window.performance.measure(measureName, measureOpts);
+          } else {
+            window.performance.measure(measureName, startMark, endMark);
+          }
         }
+      } catch (err) {
+        // NOTE: Performance metrics will be missed if an error occurs here
+        a11yEngine.errorHandler.addNonCheckError(
+          'INSTRUMENTATION_ERROR',
+          'AxeCore PerformanceTimer measure Error',
+          err,
+          true
+        );
       }
     },
     /**