diff --git a/toolkit/components/aboutperformance/content/aboutPerformance.js b/toolkit/components/aboutperformance/content/aboutPerformance.js
index 1ab4df9fb674..80cebfd550c4 100644
--- a/toolkit/components/aboutperformance/content/aboutPerformance.js
+++ b/toolkit/components/aboutperformance/content/aboutPerformance.js
@@ -585,9 +585,9 @@ var View = {
         }
 
         cachedElements.eltFPS.textContent = `Impact on framerate: ${delta.diff.jank.longestDuration + 1}/${delta.diff.jank.durations.length}${jankSuffix}.`;
-        cachedElements.eltCPU.textContent = `CPU usage: ${Math.ceil(delta.diff.jank.totalCPUTime/delta.diff.deltaT)}%.`;
-        cachedElements.eltSystem.textContent = `System usage: ${Math.ceil(delta.diff.jank.totalSystemTime/delta.diff.deltaT)}%.`;
-        cachedElements.eltCPOW.textContent = `Blocking process calls: ${Math.ceil(delta.diff.cpow.totalCPOWTime/delta.diff.deltaT)}%.`;
+        cachedElements.eltCPU.textContent = `CPU usage: ${Math.ceil(delta.diff.jank.totalCPUTime/delta.diff.deltaT/10)}%.`;
+        cachedElements.eltSystem.textContent = `System usage: ${Math.ceil(delta.diff.jank.totalSystemTime/delta.diff.deltaT/10)}%.`;
+        cachedElements.eltCPOW.textContent = `Blocking process calls: ${Math.ceil(delta.diff.cpow.totalCPOWTime/delta.diff.deltaT/10)}%.`;
       } else {
         if (delta.alerts.length == 0) {
           eltImpact.textContent = " has performed well so far.";
@@ -628,9 +628,9 @@ var View = {
         }
 
         let result = delta.diff.jank.totalCPUTime/delta.diff.deltaT;
-        cachedElements.eltCPU.textContent = `CPU usage: ${Math.ceil(delta.diff.jank.totalCPUTime/delta.diff.deltaT)}% (total ${delta.diff.jank.totalUserTime}ms).`;
-        cachedElements.eltSystem.textContent = `System usage: ${Math.ceil(delta.diff.jank.totalSystemTime/delta.diff.deltaT)}% (total ${delta.diff.jank.totalSystemTime}ms).`;
-        cachedElements.eltCPOW.textContent = `Blocking process calls: ${Math.ceil(delta.diff.cpow.totalCPOWTime/delta.diff.deltaT)}% (total ${delta.diff.cpow.totalCPOWTime}ms).`;
+        cachedElements.eltCPU.textContent = `CPU usage: ${Math.ceil(delta.diff.jank.totalCPUTime/delta.diff.deltaT/10)}% (total ${delta.diff.jank.totalUserTime}ms).`;
+        cachedElements.eltSystem.textContent = `System usage: ${Math.ceil(delta.diff.jank.totalSystemTime/delta.diff.deltaT/10)}% (total ${delta.diff.jank.totalSystemTime}ms).`;
+        cachedElements.eltCPOW.textContent = `Blocking process calls: ${Math.ceil(delta.diff.cpow.totalCPOWTime/delta.diff.deltaT/10)}% (total ${delta.diff.cpow.totalCPOWTime}ms).`;
       }
     }
     this._insertElements(toAdd, id);