diff --git a/js/perf/core.js b/js/perf/core.js
index 9b4b5489c..b7e64547e 100644
--- a/js/perf/core.js
+++ b/js/perf/core.js
@@ -12,15 +12,15 @@ let METRICS = {
     overviewLatencyFirst:
     { description: "Time to first frame after triggering overview, first time",
       units: "us" },
-    overviewFramesFirst:
-    { description: "Frames displayed when going to overview, first time",
-      units: "frames" },
+    overviewFpsFirst:
+    { description: "Frame rate when going to the overview, first time",
+      units: "frames / s" },
     overviewLatencySubsequent:
     { description: "Time to first frame after triggering overview, second time",
       units: "us"},
-    overviewFramesSubsequent:
-    { description: "Frames displayed when going to overview, second time",
-      units: "us" },
+    overviewFpsSubsequent:
+    { description: "Frames rate when going to the overview, second time",
+      units: "frames / s" },
     usedAfterOverview:
     { description: "Malloc'ed bytes after the overview is shown once",
       units: "B" },
@@ -34,14 +34,17 @@ function run() {
     Scripting.defineScriptEvent("overviewShowDone", "Overview finished showing");
     Scripting.defineScriptEvent("afterShowHide", "After a show/hide cycle for the overview");
 
+    Main.overview.connect('shown', function() {
+                              Scripting.scriptEvent('overviewShowDone');
+                          });
+
     yield Scripting.sleep(1000);
     yield Scripting.waitLeisure();
     for (let i = 0; i < 2; i++) {
         Scripting.scriptEvent('overviewShowStart');
         Main.overview.show();
-        yield Scripting.waitLeisure();
-        Scripting.scriptEvent('overviewShowDone');
 
+        yield Scripting.waitLeisure();
         Main.overview.hide();
         yield Scripting.waitLeisure();
 
@@ -53,31 +56,27 @@ function run() {
 }
 
 let showingOverview = false;
+let finishedShowingOverview = false;
 let overviewShowStart;
 let overviewFrames;
 let overviewLatency;
 let mallocUsedSize = 0;
 let overviewShowCount = 0;
 let firstOverviewUsedSize;
+let haveSwapComplete = false;
 
 function script_overviewShowStart(time) {
     showingOverview = true;
+    finishedShowingOverview = false;
     overviewShowStart = time;
     overviewFrames = 0;
 }
 
 function script_overviewShowDone(time) {
-    showingOverview = false;
-
-    overviewShowCount++;
-
-    if (overviewShowCount == 1) {
-        METRICS.overviewLatencyFirst.value = overviewLatency;
-        METRICS.overviewFramesFirst.value = overviewFrames;
-    } else {
-        METRICS.overviewLatencySubsequent.value = overviewLatency;
-        METRICS.overviewFramesSubsequent.value = overviewFrames;
-    }
+    // We've set up the state at the end of the zoom out, but we
+    // need to wait for one more frame to paint before we count
+    // ourselves as done.
+    finishedShowingOverview = true;
 }
 
 function script_afterShowHide(time) {
@@ -92,11 +91,50 @@ function malloc_usedSize(time, bytes) {
     mallocUsedSize = bytes;
 }
 
-function clutter_stagePaintDone(time) {
+function _frameDone(time) {
     if (showingOverview) {
         if (overviewFrames == 0)
             overviewLatency = time - overviewShowStart;
 
         overviewFrames++;
     }
+
+    if (finishedShowingOverview) {
+        showingOverview = false;
+        finishedShowingOverview = false;
+        overviewShowCount++;
+
+        let dt = (time - (overviewShowStart + overviewLatency)) / 1000000;
+
+        // If we see a start frame and an end frame, that would
+        // be 1 frame for a FPS computation, hence the '- 1'
+        let fps = (overviewFrames - 1) / dt;
+
+        if (overviewShowCount == 1) {
+            METRICS.overviewLatencyFirst.value = overviewLatency;
+            METRICS.overviewFpsFirst.value = fps;
+        } else {
+            METRICS.overviewLatencySubsequent.value = overviewLatency;
+            METRICS.overviewFpsSubsequent.value = fps;
+        }
+    }
+}
+
+function glx_swapComplete(time, swapTime) {
+    haveSwapComplete = true;
+
+    _frameDone(swapTime);
+}
+
+function clutter_stagePaintDone(time) {
+    // If we aren't receiving GLXBufferSwapComplete events, then we approximate
+    // the time the user sees a frame with the time we finished doing drawing
+    // commands for the frame. This doesn't take into account the time for
+    // the GPU to finish painting, and the time for waiting for the buffer
+    // swap, but if this are uniform - every frame takes the same time to draw -
+    // then it won't upset our FPS calculation, though the latency value
+    // will be slightly too low.
+
+    if (!haveSwapComplete)
+        _frameDone(time);
 }