--- a/toolkit/components/places/nsPlacesAutoComplete.js
+++ b/toolkit/components/places/nsPlacesAutoComplete.js
@@ -3,16 +3,18 @@
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 Components.utils.import("resource://gre/modules/Services.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PlacesUtils",
                                   "resource://gre/modules/PlacesUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "TelemetryStopwatch",
+                                  "resource://gre/modules/TelemetryStopwatch.jsm");
 
 ////////////////////////////////////////////////////////////////////////////////
 //// Constants
 
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cr = Components.results;
 
@@ -72,16 +74,19 @@ const kTitleTagsSeparator = " \u2013 ";
 const kBrowserUrlbarBranch = "browser.urlbar.";
 // Toggle autocomplete.
 const kBrowserUrlbarAutocompleteEnabledPref = "autocomplete.enabled";
 // Toggle autoFill.
 const kBrowserUrlbarAutofillPref = "autoFill";
 // Whether to search only typed entries.
 const kBrowserUrlbarAutofillTypedPref = "autoFill.typed";
 
+// The Telemetry histogram for urlInlineComplete query on domain
+const DOMAIN_QUERY_TELEMETRY = "PLACES_AUTOCOMPLETE_URLINLINE_DOMAIN_QUERY_TIME_MS";
+
 ////////////////////////////////////////////////////////////////////////////////
 //// Globals
 
 XPCOMUtils.defineLazyServiceGetter(this, "gTextURIService",
                                    "@mozilla.org/intl/texttosuburi;1",
                                    "nsITextToSubURI");
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1386,25 +1391,30 @@ urlInlineComplete.prototype = {
     let query = this._syncQuery;
     query.params.search_string = this._currentSearchString.toLowerCase();
 
     // Domains have no "/" in them.
     let lastSlashIndex = this._currentSearchString.lastIndexOf("/");
     if (lastSlashIndex == -1) {
       var hasDomainResult = false;
       var domain, untrimmedDomain;
+      TelemetryStopwatch.start(DOMAIN_QUERY_TELEMETRY);
       try {
+        // Execute the query synchronously.
+        // This is by design, to avoid race conditions between the
+        // user typing and the connection searching for the result.
         hasDomainResult = query.executeStep();
         if (hasDomainResult) {
           domain = query.getString(0);
           untrimmedDomain = query.getString(1);
         }
       } finally {
         query.reset();
       }
+      TelemetryStopwatch.finish(DOMAIN_QUERY_TELEMETRY);
 
       if (hasDomainResult) {
         // We got a match for a domain, we can add it immediately.
         // If the untrimmed value doesn't preserve the user's input just
         // ignore it and complete to the found domain.
         if (untrimmedDomain &&
             !untrimmedDomain.toLowerCase().contains(this._originalSearchString.toLowerCase())) {
           untrimmedDomain = null;

--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -1828,16 +1828,23 @@
   },
   "PLACES_AUTOCOMPLETE_1ST_RESULT_TIME_MS": {
     "kind": "exponential",
     "low": 50,
     "high": "500",
     "n_buckets": 10,
     "description": "PLACES: Time for first autocomplete result if > 50ms (ms)"
   },
+  "PLACES_AUTOCOMPLETE_URLINLINE_DOMAIN_QUERY_TIME_MS": {
+    "kind": "exponential",
+    "low": 50,
+    "high": 2000,
+    "n_buckets": 10,
+    "description": "PLACES: Duration of the domain query for the url inline autocompletion (ms)"
+  },
   "PLACES_IDLE_FRECENCY_DECAY_TIME_MS": {
     "kind": "exponential",
     "low": 50,
     "high": "10000",
     "n_buckets": 10,
     "description": "PLACES: Time to decay all frecencies values on idle (ms)"
   },
   "PLACES_IDLE_MAINTENANCE_TIME_MS": {