stack-timing.diff

diff --git a/dom/performance/Performance.cpp b/dom/performance/Performance.cpp
--- a/dom/performance/Performance.cpp
+++ b/dom/performance/Performance.cpp
@@ -215,20 +215,68 @@ void Performance::Mark(const nsAString& 
   }
 
   RefPtr<PerformanceMark> performanceMark =
       new PerformanceMark(GetParentObject(), aName, Now());
   InsertUserEntry(performanceMark);
 
 #ifdef MOZ_GECKO_PROFILER
   if (profiler_is_active()) {
+
     nsCOMPtr<EventTarget> et = do_QueryInterface(GetOwner());
     nsCOMPtr<nsIDocShell> docShell =
         nsContentUtils::GetDocShellForEventTarget(et);
     DECLARE_DOCSHELL_AND_HISTORY_ID(docShell);
+
+    {
+      auto timerA = TimeStamp::Now();
+      size_t iterations = 1000;
+
+      for(size_t i = 0; i < iterations; i++) {
+        profiler_add_marker(
+          "UserTiming",
+          js::ProfilingStackFrame::Category::DOM,
+          MakeUnique<UserTimingMarkerPayload>(
+            aName,
+            TimeStamp::Now(),
+            docShellId,
+            docShellHistoryId,
+            profiler_get_backtrace()
+          )
+        );
+      }
+
+      auto timerB = TimeStamp::Now();
+
+      for(size_t i = 0; i < iterations; i++) {
+        profiler_add_marker(
+          "UserTiming",
+          js::ProfilingStackFrame::Category::DOM,
+          MakeUnique<UserTimingMarkerPayload>(
+            aName,
+            TimeStamp::Now(),
+            docShellId,
+            docShellHistoryId
+          )
+        );
+      }
+
+      auto timerC = TimeStamp::Now();
+
+      auto timingWith = (timerB - timerA).ToMicroseconds();
+      auto timingWithout = (timerC - timerB).ToMicroseconds();
+      auto timePer = (timingWith - timingWithout) / iterations;
+      auto percentage = 100.0 * timingWith / timingWithout;
+
+      printf("!!! Generate %zu markers with stack    %ldμs\n", iterations, (long) timingWith);
+      printf("!!! Generate %zu markers without stack %ldμs\n", iterations, (long) timingWithout);
+      printf("!!! Time per stack                      %fμs\n", timePer);
+      printf("!!! Percentage difference               %ld%%\n\n", (long) percentage);
+    }
+
     profiler_add_marker(
         "UserTiming", js::ProfilingStackFrame::Category::DOM,
         MakeUnique<UserTimingMarkerPayload>(aName, TimeStamp::Now(), docShellId,
                                             docShellHistoryId));
   }
 #endif
 }
 
diff --git a/tools/profiler/public/ProfilerMarkerPayload.h b/tools/profiler/public/ProfilerMarkerPayload.h
--- a/tools/profiler/public/ProfilerMarkerPayload.h
+++ b/tools/profiler/public/ProfilerMarkerPayload.h
@@ -157,19 +157,20 @@ class DOMEventMarkerPayload : public Tra
   nsString mEventType;
 };
 
 class UserTimingMarkerPayload : public ProfilerMarkerPayload {
  public:
   UserTimingMarkerPayload(const nsAString& aName,
                           const mozilla::TimeStamp& aStartTime,
                           const mozilla::Maybe<nsID>& aDocShellId,
-                          const mozilla::Maybe<uint32_t>& aDocShellHistoryId)
+                          const mozilla::Maybe<uint32_t>& aDocShellHistoryId,
+                          UniqueProfilerBacktrace aStack = nullptr)
       : ProfilerMarkerPayload(aStartTime, aStartTime, aDocShellId,
-                              aDocShellHistoryId),
+                              aDocShellHistoryId, std::move(aStack)),
         mEntryType("mark"),
         mName(aName) {}
 
   UserTimingMarkerPayload(const nsAString& aName,
                           const mozilla::Maybe<nsString>& aStartMark,
                           const mozilla::Maybe<nsString>& aEndMark,
                           const mozilla::TimeStamp& aStartTime,
                           const mozilla::TimeStamp& aEndTime,