diff --git a/toolkit/components/aboutperformance/content/aboutPerformance.js b/toolkit/components/aboutperformance/content/aboutPerformance.js
index e0d34128a39c..0693af318b11 100644
--- a/toolkit/components/aboutperformance/content/aboutPerformance.js
+++ b/toolkit/components/aboutperformance/content/aboutPerformance.js
@@ -14,8 +14,6 @@ const { PerformanceStats } = Cu.import("resource://gre/modules/PerformanceStats.
 const { Services } = Cu.import("resource://gre/modules/Services.jsm", {});
 const { Task } = Cu.import("resource://gre/modules/Task.jsm", {});
 const { ObjectUtils } = Cu.import("resource://gre/modules/ObjectUtils.jsm", {});
-const { Memory } = Cu.import("resource://gre/modules/Memory.jsm");
-const { DownloadUtils } = Cu.import("resource://gre/modules/DownloadUtils.jsm");
 
 // about:performance observes notifications on this topic.
 // if a notification is sent, this causes the page to be updated immediately,
@@ -944,123 +942,7 @@ var Control = {
   _displayMode: MODE_GLOBAL,
 };
 
-/**
- * This functionality gets memory related information of sub-processes and
- * updates the performance table regularly.
- * If the page goes hidden, it also handles visibility change by not
- * querying the content processes unnecessarily.
- */
-var SubprocessMonitor = {
-  _timeout: null,
-
-  /**
-   * Init will start the process of updating the table if the page is not hidden,
-   * and set up an event listener for handling visibility changes.
-   */
-  init: function() {
-    if (!document.hidden) {
-      SubprocessMonitor.updateTable();
-    }
-    document.addEventListener("visibilitychange", SubprocessMonitor.handleVisibilityChange);
-  },
-
-  /**
-   * This function updates the table after an interval if the page is visible
-   * and clears the interval otherwise.
-   */
-  handleVisibilityChange: function() {
-    if (!document.hidden) {
-      SubprocessMonitor.queueUpdate();
-    } else {
-      clearTimeout(this._timeout);
-      this._timeout = null;
-    }
-  },
-
-  /**
-   * This function queues a timer to request the next summary using updateTable
-   * after some delay.
-   */
-  queueUpdate: function() {
-    this._timeout = setTimeout(() => this.updateTable(), UPDATE_INTERVAL_MS);
-  },
-
-  /**
-   * This is a helper function for updateTable, which updates a particular row.
-   * @param {<tr> node} row The row to be updated.
-   * @param {object} summaries The object with the updated RSS and USS values.
-   * @param {string} pid The pid represented by the row for which we update.
-   */
-  updateRow: function(row, summaries, pid) {
-    row.cells[0].textContent = pid;
-    let RSSval = DownloadUtils.convertByteUnits(summaries[pid].rss);
-    row.cells[1].textContent = RSSval.join(" ");
-    let USSval = DownloadUtils.convertByteUnits(summaries[pid].uss);
-    row.cells[2].textContent = USSval.join(" ");
-  },
-
-  /**
-   * This function adds a row to the subprocess-performance table for every new pid
-   * and populates and regularly updates it with RSS/USS measurements.
-   */
-  updateTable: function() {
-    if (!document.hidden) {
-      Memory.summary().then((summaries) => {
-        if (!(Object.keys(summaries).length)) {
-          // The summaries list was empty, which means we timed out getting
-          // the memory reports. We'll try again later.
-          SubprocessMonitor.queueUpdate();
-          return;
-        }
-        let resultTable = document.getElementById("subprocess-reports");
-        let recycle = [];
-        // We first iterate the table to check if summaries exist for rowPids,
-        // if yes, update them and delete the pid's summary or else hide the row
-        // for recycling it. Start at row 1 instead of 0 (to skip the header row).
-        for (let i = 1, row; row = resultTable.rows[i]; i++) {
-          let rowPid = row.dataset.pid;
-          let summary = summaries[rowPid];
-          if (summary) {
-            // Now we update the values in the row, which is hardcoded for now,
-            // but we might want to make this more adaptable in the future.
-            SubprocessMonitor.updateRow(row, summaries, rowPid);
-            delete summaries[rowPid];
-          } else {
-            // Take this unnecessary row, hide it and stash it for potential re-use.
-            row.hidden = true;
-            recycle.push(row);
-          }
-        }
-        // For the remaining pids in summaries, we choose from the recyclable
-        // (hidden) nodes, and if they get exhausted, append a row to the table.
-        for (let pid in summaries) {
-          let row = recycle.pop();
-          if (row) {
-            row.hidden = false;
-          } else {
-            // We create a new row here, and set it to row
-            row = document.createElement("tr");
-            // Insert cell for pid
-            row.insertCell();
-            // Insert a cell for USS.
-            row.insertCell();
-            // Insert another cell for RSS.
-            row.insertCell();
-          }
-          row.dataset.pid = pid;
-          // Update the row and put it at the bottom
-          SubprocessMonitor.updateRow(row, summaries, pid);
-          resultTable.appendChild(row);
-        }
-      });
-      SubprocessMonitor.queueUpdate();
-    }
-  },
-};
-
 var go = Task.async(function*() {
-
-  SubprocessMonitor.init();
   Control.init();
 
   // Setup a hook to allow tests to configure and control this page
diff --git a/toolkit/components/aboutperformance/content/aboutPerformance.xhtml b/toolkit/components/aboutperformance/content/aboutPerformance.xhtml
index 721320534b48..048b0905c106 100644
--- a/toolkit/components/aboutperformance/content/aboutPerformance.xhtml
+++ b/toolkit/components/aboutperformance/content/aboutPerformance.xhtml
@@ -7,21 +7,9 @@
 <html xmlns="http://www.w3.org/1999/xhtml">
   <head>
     <title>about:performance</title>
-    <link rel="icon" type="image/png" id="favicon"
-          href="chrome://branding/content/icon32.png"/>
-    <link rel="stylesheet" href="chrome://global/skin/in-content/common.css"
-          type="text/css"/>
     <script type="text/javascript;version=1.8" src="chrome://global/content/aboutPerformance.js"></script>
     <style>
       @import url("chrome://global/skin/in-content/common.css");
-
-      html {
-        --aboutSupport-table-background: #ebebeb;
-        background-color: var(--in-content-page-background);
-      }
-      body {
-        margin: 40px 48px;
-      }
       .hidden {
         display: none;
       }
@@ -102,59 +90,9 @@
       li.delta[impact="11"] {
         border-left-color: rgb(255, 0, 0);
       }
-
-      #subprocess-reports {
-        background-color: var(--aboutSupport-table-background);
-        color: var(--in-content-text-color);
-        font: message-box;
-        text-align: start;
-        border: 1px solid var(--in-content-border-color);
-        border-spacing: 0px;
-        float: right;
-        margin-bottom: 20px;
-        -moz-margin-start: 20px;
-        -moz-margin-end: 0;
-        width: 100%;
-      }
-      #subprocess-reports:-moz-dir(rtl) {
-        float: left;
-      }
-      #subprocess-reports th,
-      #subprocess-reports td {
-        border: 1px solid var(--in-content-border-color);
-        padding: 4px;
-      }
-      #subprocess-reports thead th {
-        text-align: center;
-      }
-      #subprocess-reports th {
-        text-align: start;
-        background-color: var(--in-content-table-header-background);
-        color: var(--in-content-selected-text);
-      }
-      #subprocess-reports th.column {
-        white-space: nowrap;
-        width: 0px;
-      }
-      #subprocess-reports td {
-        background-color: #ebebeb;
-        text-align: start;
-        border-color: var(--in-content-table-border-dark-color);
-        border-spacing: 40px;
-      }
     </style>
   </head>
   <body onload="go()">
-    <div>
-      <h2>Memory usage of Subprocesses</h2>
-      <table id="subprocess-reports">
-        <tr>
-          <th>Process ID</th>
-          <th title="RSS measures the pages resident in the main memory for the process">Resident Set Size</th>
-          <th title="USS gives a count of unshared pages, unique to the process">Unique Set Size</th>
-        </tr>
-      </table>
-    </div>
     <div>
       <input type="checkbox" checked="false" id="check-display-recent"></input> 
       <label for="check-display-recent" id="label-display-recent">Display only the last few seconds.</label>
diff --git a/toolkit/content/process-content.js b/toolkit/content/process-content.js
index 2ff8f908a956..9262d0b7f90b 100644
--- a/toolkit/content/process-content.js
+++ b/toolkit/content/process-content.js
@@ -31,35 +31,15 @@ if (gInContentProcess) {
     init() {
       for (let topic of this.TOPICS) {
         Services.obs.addObserver(this, topic, false);
-        Services.cpmm.addMessageListener("Memory:GetSummary", this);
       }
     },
 
     uninit() {
       for (let topic of this.TOPICS) {
         Services.obs.removeObserver(this, topic);
-        Services.cpmm.removeMessageListener("Memory:GetSummary", this);
       }
     },
 
-    receiveMessage(msg) {
-      if (msg.name != "Memory:GetSummary") {
-        return;
-      }
-      let pid = Services.appinfo.processID;
-      let memMgr = Cc["@mozilla.org/memory-reporter-manager;1"]
-                     .getService(Ci.nsIMemoryReporterManager);
-      let rss = memMgr.resident;
-      let uss = memMgr.residentUnique;
-      Services.cpmm.sendAsyncMessage("Memory:Summary", {
-        pid,
-        summary: {
-          uss,
-          rss,
-        }
-      });
-    },
-
     observe(subject, topic, data) {
       switch (topic) {
         case "inner-window-destroyed": {
diff --git a/toolkit/modules/moz.build b/toolkit/modules/moz.build
index 886a91f12dd3..677c80e7ea69 100644
--- a/toolkit/modules/moz.build
+++ b/toolkit/modules/moz.build
@@ -52,7 +52,6 @@ EXTRA_JS_MODULES += [
     'LoadContextInfo.jsm',
     'Locale.jsm',
     'Log.jsm',
-    'Memory.jsm',
     'NewTabUtils.jsm',
     'NLP.jsm',
     'ObjectUtils.jsm',