diff --git a/devtools/client/responsive.html/manager.js b/devtools/client/responsive.html/manager.js
index 1772c4f3b3ee..b3421950c15c 100644
--- a/devtools/client/responsive.html/manager.js
+++ b/devtools/client/responsive.html/manager.js
@@ -87,36 +87,18 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
    */
   async openIfNeeded(window, tab, options = {}) {
     if (!tab.linkedBrowser.isRemoteBrowser) {
-      this.showRemoteOnlyNotification(window, tab, options);
+      await this.showRemoteOnlyNotification(window, tab, options);
       return promise.reject(new Error("RDM only available for remote tabs."));
     }
     if (!this.isActiveForTab(tab)) {
       this.initMenuCheckListenerFor(window);
 
-      // Track whether a toolbox was opened before RDM was opened.
-      const toolbox = gDevTools.getToolbox(TargetFactory.forTab(tab));
-      const hostType = toolbox ? toolbox.hostType : "none";
-      const hasToolbox = !!toolbox;
-      const tel = this._telemetry;
-      if (hasToolbox) {
-        tel.scalarAdd("devtools.responsive.toolbox_opened_first", 1);
-      }
-
-      tel.recordEvent("devtools.main", "activate", "responsive_design", null, {
-        "host": hostType,
-        "width": Math.ceil(window.outerWidth / 50) * 50,
-        "session_id": toolbox ? toolbox.sessionId : -1
-      });
-
-      // Track opens keyed by the UI entry point used.
-      let { trigger } = options;
-      if (!trigger) {
-        trigger = "unknown";
-      }
-      tel.keyedScalarAdd("devtools.responsive.open_trigger", trigger, 1);
-
       const ui = new ResponsiveUI(window, tab);
       this.activeTabs.set(tab, ui);
+
+      // Explicitly not await on telemetry to avoid delaying RDM opening
+      this.recordTelemetryOpen(window, tab, options);
+
       await this.setMenuCheckFor(tab, window);
       await ui.inited;
       this.emit("on", { tab });
@@ -125,6 +107,38 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
     return this.getResponsiveUIForTab(tab);
   },
 
+  /**
+   * Record all telemetry probes related to RDM opening.
+   */
+  async recordTelemetryOpen(window, tab, options) {
+    // Track whether a toolbox was opened before RDM was opened.
+    const isKnownTab = TargetFactory.isKnownTab(tab);
+    let toolbox;
+    if (isKnownTab) {
+      const target = await TargetFactory.forTab(tab);
+      toolbox = gDevTools.getToolbox(target);
+    }
+    const hostType = toolbox ? toolbox.hostType : "none";
+    const hasToolbox = !!toolbox;
+    const tel = this._telemetry;
+    if (hasToolbox) {
+      tel.scalarAdd("devtools.responsive.toolbox_opened_first", 1);
+    }
+
+    tel.recordEvent("devtools.main", "activate", "responsive_design", null, {
+      "host": hostType,
+      "width": Math.ceil(window.outerWidth / 50) * 50,
+      "session_id": toolbox ? toolbox.sessionId : -1
+    });
+
+    // Track opens keyed by the UI entry point used.
+    let { trigger } = options;
+    if (!trigger) {
+      trigger = "unknown";
+    }
+    tel.keyedScalarAdd("devtools.responsive.open_trigger", trigger, 1);
+  },
+
   /**
    * Closes the responsive UI, if not already closed.
    *
@@ -144,15 +158,6 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
    */
   async closeIfNeeded(window, tab, options = {}) {
     if (this.isActiveForTab(tab)) {
-      const isKnownTab = TargetFactory.isKnownTab(tab);
-      const target = TargetFactory.forTab(tab);
-      const toolbox = gDevTools.getToolbox(target);
-
-      if (!toolbox && !isKnownTab) {
-        // Destroy the tabTarget to avoid a memory leak.
-        target.destroy();
-      }
-
       const ui = this.activeTabs.get(tab);
       const destroyed = await ui.destroy(options);
       if (!destroyed) {
@@ -160,14 +165,6 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
         return;
       }
 
-      const hostType = toolbox ? toolbox.hostType : "none";
-      const t = this._telemetry;
-      t.recordEvent("devtools.main", "deactivate", "responsive_design", null, {
-        "host": hostType,
-        "width": Math.ceil(window.outerWidth / 50) * 50,
-        "session_id": toolbox ? toolbox.sessionId : -1
-      });
-
       this.activeTabs.delete(tab);
 
       if (!this.isActiveForWindow(window)) {
@@ -175,9 +172,29 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
       }
       this.emit("off", { tab });
       await this.setMenuCheckFor(tab, window);
+
+      // Explicitly not await on telemetry to avoid delaying RDM closing
+      this.recordTelemetryClose(window, tab);
     }
   },
 
+  async recordTelemetryClose(window, tab) {
+    const isKnownTab = TargetFactory.isKnownTab(tab);
+    let toolbox;
+    if (isKnownTab) {
+      const target = await TargetFactory.forTab(tab);
+      toolbox = gDevTools.getToolbox(target);
+    }
+
+    const hostType = toolbox ? toolbox.hostType : "none";
+    const t = this._telemetry;
+    t.recordEvent("devtools.main", "deactivate", "responsive_design", null, {
+      "host": hostType,
+      "width": Math.ceil(window.outerWidth / 50) * 50,
+      "session_id": toolbox ? toolbox.sessionId : -1
+    });
+  },
+
   /**
    * Returns true if responsive UI is active for a given tab.
    *
@@ -238,7 +255,7 @@ const ResponsiveUIManager = exports.ResponsiveUIManager = {
   },
 
   showRemoteOnlyNotification(window, tab, { trigger } = {}) {
-    showNotification(window, tab, {
+    return showNotification(window, tab, {
       toolboxButton: trigger == "toolbox",
       msg: l10n.getStr("responsive.remoteOnly"),
       priority: PriorityLevels.PRIORITY_CRITICAL_MEDIUM,
@@ -374,7 +391,8 @@ ResponsiveUI.prototype = {
     // If our tab is about to be closed, there's not enough time to exit
     // gracefully, but that shouldn't be a problem since the tab will go away.
     // So, skip any waiting when we're about to close the tab.
-    const isWindowClosing = options && options.reason === "unload";
+    const isTabDestroyed = !this.tab.linkedBrowser;
+    const isWindowClosing = (options && options.reason === "unload") || isTabDestroyed;
     const isTabContentDestroying =
       isWindowClosing || (options && (options.reason === "TabClose" ||
                                       options.reason === "BeforeTabRemotenessChange"));
diff --git a/devtools/client/responsive.html/utils/notification.js b/devtools/client/responsive.html/utils/notification.js
index aaddcf9e07e5..8e1170175a99 100644
--- a/devtools/client/responsive.html/utils/notification.js
+++ b/devtools/client/responsive.html/utils/notification.js
@@ -22,7 +22,7 @@ loader.lazyRequireGetter(this, "gDevTools", "devtools/client/framework/devtools"
  *        - `priority`: Priority level for the notification, which affects the icon and
  *                      overall appearance.
  */
-function showNotification(window, tab, { toolboxButton, msg, priority } = {}) {
+async function showNotification(window, tab, { toolboxButton, msg, priority } = {}) {
   // Default to using the browser's per-tab notification box
   let nbox = window.gBrowser.getNotificationBox(tab.linkedBrowser);
 
@@ -30,7 +30,7 @@ function showNotification(window, tab, { toolboxButton, msg, priority } = {}) {
   // toolbox for the tab.  If one exists, use the toolbox's notification box so that the
   // message is placed closer to the action taken by the user.
   if (toolboxButton) {
-    const target = TargetFactory.forTab(tab);
+    const target = await TargetFactory.forTab(tab);
     const toolbox = gDevTools.getToolbox(target);
     if (toolbox) {
       nbox = toolbox.notificationBox;