--- a/browser/base/content/browser-sync.js
+++ b/browser/base/content/browser-sync.js
@@ -76,16 +76,32 @@ var gSync = {
       delete this[prop];
       this.__defineGetter__(prop, function() {
         delete this[prop];
         return this[prop] = document.getElementById("appMenu-fxa-" + suffix);
       });
     }
   },
 
+  _definePrefGetters() {
+    XPCOMUtils.defineLazyPreferenceGetter(this, "UNSENDABLE_URL_REGEXP",
+        "services.sync.engine.tabs.filteredUrls", null, null, rx => {
+          try {
+            return new RegExp(rx, "i");
+          } catch (e) {
+            Cu.reportError(`Failed to build url filter regexp for send tab: ${e}`);
+            return null;
+          }
+        });
+    XPCOMUtils.defineLazyPreferenceGetter(this, "FXA_CONNECT_DEVICE_URI",
+        "identity.fxaccounts.remote.connectdevice.uri");
+    XPCOMUtils.defineLazyPreferenceGetter(this, "PRODUCT_INFO_BASE_URL",
+        "app.productInfo.baseURL");
+  },
+
   _maybeUpdateUIState() {
     // Update the UI.
     if (UIState.isReady()) {
       const state = UIState.get();
       // If we are not configured, the UI is already in the right state when
       // we open the window. We can avoid a repaint.
       if (state.status != UIState.STATUS_NOT_CONFIGURED) {
         this.updateAllUI(state);
@@ -98,16 +114,17 @@ var gSync = {
       return;
     }
 
     for (let topic of this._obs) {
       Services.obs.addObserver(this, topic, true);
     }
 
     this._generateNodeGetters();
+    this._definePrefGetters();
 
     // initial label for the sync buttons.
     let broadcaster = document.getElementById("sync-status");
     broadcaster.setAttribute("label", this.syncStrings.GetStringFromName("syncnow.label"));
 
     this._maybeUpdateUIState();
 
     EnsureFxAccountsWebChannel();
@@ -272,23 +289,23 @@ var gSync = {
     let url = await fxAccounts.promiseAccountsManageDevicesURI(entryPoint);
     switchToTabHavingURI(url, true, {
       replaceQueryString: true,
       triggeringPrincipal: Services.scriptSecurityManager.getSystemPrincipal(),
     });
   },
 
   openConnectAnotherDevice(entryPoint) {
-    let url = new URL(Services.prefs.getCharPref("identity.fxaccounts.remote.connectdevice.uri"));
+    let url = new URL(this.FXA_CONNECT_DEVICE_URI);
     url.searchParams.append("entrypoint", entryPoint);
     openUILinkIn(url.href, "tab");
   },
 
   openSendToDevicePromo() {
-    let url = Services.prefs.getCharPref("app.productInfo.baseURL");
+    let url = this.PRODUCT_INFO_BASE_URL;
     url += "send-tabs/?utm_source=" + Services.appinfo.name.toLowerCase();
     switchToTabHavingURI(url, true, { replaceQueryString: true });
   },
 
   sendTabToDevice(url, clientId, title) {
     Weave.Service.clientsEngine.sendURIToClientForDisplay(url, clientId, title).catch(e => {
       console.error("Could not send tab to device", e);
     });
@@ -428,28 +445,24 @@ var gSync = {
   isSendableURI(aURISpec) {
     if (!aURISpec) {
       return false;
     }
     // Disallow sending tabs with more than 65535 characters.
     if (aURISpec.length > 65535) {
       return false;
     }
-    try {
-      // Filter out un-sendable URIs -- things like local files, object urls, etc.
-      const unsendableRegexp = new RegExp(
-        Services.prefs.getCharPref("services.sync.engine.tabs.filteredUrls"), "i");
-      return !unsendableRegexp.test(aURISpec);
-    } catch (e) {
-      // The preference has been removed, or is an invalid regexp, so we log an
-      // error and treat it as a valid URI -- and the more problematic case is
-      // the length, which we've already addressed.
-      Cu.reportError(`Failed to build url filter regexp for send tab: ${e}`);
-      return true;
+    if (this.UNSENDABLE_URL_REGEXP) {
+      return !this.UNSENDABLE_URL_REGEXP.test(aURISpec);
     }
+    // The preference has been removed, or is an invalid regexp, so we treat it
+    // as a valid URI. We've already logged an error when trying to construct
+    // the regexp, and the more problematic case is the length, which we've
+    // already addressed.
+    return true;
   },
 
   // "Send Tab to Device" menu item
   updateTabContextMenu(aPopupMenu, aTargetTab) {
     const enabled = !this.syncConfiguredAndLoading &&
                     this.isSendableURI(aTargetTab.linkedBrowser.currentURI.spec);
 
     document.getElementById("context_sendTabToDevice").disabled = !enabled;