--- a/browser/components/preferences/in-content/main.js
+++ b/browser/components/preferences/in-content/main.js
@@ -1188,41 +1188,29 @@ var gMainPane = {
 
   updatePerformanceSettingsBox({ duringChangeEvent }) {
     let defaultPerformancePref =
       document.getElementById("browser.preferences.defaultPerformanceSettings.enabled");
     let performanceSettings = document.getElementById("performanceSettings");
     let processCountPref = document.getElementById("dom.ipc.processCount");
     if (defaultPerformancePref.value) {
       let accelerationPref = document.getElementById("layers.acceleration.disabled");
-      // Unset the value so process count will be decided by e10s rollout.
+      // Unset the value so process count will be decided by the platform.
       processCountPref.value = processCountPref.defaultValue;
       accelerationPref.value = accelerationPref.defaultValue;
       performanceSettings.hidden = true;
     } else {
-      let e10sRolloutProcessCountPref =
-        document.getElementById("dom.ipc.processCount.web");
-      // Take the e10s rollout value as the default value (if it exists),
-      // but don't overwrite the user set value.
-      if (duringChangeEvent &&
-        e10sRolloutProcessCountPref.value &&
-        processCountPref.value == processCountPref.defaultValue) {
-        processCountPref.value = e10sRolloutProcessCountPref.value;
-      }
       performanceSettings.hidden = false;
     }
   },
 
   buildContentProcessCountMenuList() {
     if (Services.appinfo.browserTabsRemoteAutostart) {
       let processCountPref = document.getElementById("dom.ipc.processCount");
-      let e10sRolloutProcessCountPref =
-        document.getElementById("dom.ipc.processCount.web");
-      let defaultProcessCount =
-        e10sRolloutProcessCountPref.value || processCountPref.defaultValue;
+      let defaultProcessCount = processCountPref.defaultValue;
       let bundlePreferences = document.getElementById("bundlePreferences");
       let label = bundlePreferences.getFormattedString("defaultContentProcessCount",
         [defaultProcessCount]);
       let contentProcessCount =
         document.querySelector(`#contentProcessCount > menupopup >
                                 menuitem[value="${defaultProcessCount}"]`);
       contentProcessCount.label = label;
 

--- a/browser/components/preferences/in-content/tests/browser_performance_e10srollout.js
+++ b/browser/components/preferences/in-content/tests/browser_performance_e10srollout.js
@@ -4,79 +4,52 @@ const DEFAULT_PROCESS_COUNT = Services.p
 add_task(async function() {
   await SpecialPowers.pushPrefEnv({set: [
     ["layers.acceleration.disabled", DEFAULT_HW_ACCEL_PREF],
     ["dom.ipc.processCount", DEFAULT_PROCESS_COUNT],
     ["browser.preferences.defaultPerformanceSettings.enabled", true],
   ]});
 });
 
-add_task(async function() {
-  Services.prefs.clearUserPref("dom.ipc.processCount");
-  Services.prefs.setIntPref("dom.ipc.processCount.web", DEFAULT_PROCESS_COUNT + 1);
+add_task(async function testPrefsAreDefault() {
+  Services.prefs.setIntPref("dom.ipc.processCount", DEFAULT_PROCESS_COUNT);
   Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", true);
 
   let prefs = await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
   is(prefs.selectedPane, "paneGeneral", "General pane was selected");
 
   let doc = gBrowser.contentDocument;
   let useRecommendedPerformanceSettings = doc.querySelector("#useRecommendedPerformanceSettings");
 
   is(Services.prefs.getBoolPref("browser.preferences.defaultPerformanceSettings.enabled"), true,
-    "pref value should be true before clicking on checkbox");
+     "pref value should be true before clicking on checkbox");
   ok(useRecommendedPerformanceSettings.checked, "checkbox should be checked before clicking on checkbox");
 
   useRecommendedPerformanceSettings.click();
 
   let performanceSettings = doc.querySelector("#performanceSettings");
   is(performanceSettings.hidden, false, "performance settings section is shown");
 
   is(Services.prefs.getBoolPref("browser.preferences.defaultPerformanceSettings.enabled"), false,
      "pref value should be false after clicking on checkbox");
   ok(!useRecommendedPerformanceSettings.checked, "checkbox should not be checked after clicking on checkbox");
 
   let contentProcessCount = doc.querySelector("#contentProcessCount");
   is(contentProcessCount.disabled, false, "process count control should be enabled");
-  is(Services.prefs.getIntPref("dom.ipc.processCount"), DEFAULT_PROCESS_COUNT + 1, "e10s rollout value should be default value");
-  is(contentProcessCount.selectedItem.value, DEFAULT_PROCESS_COUNT + 1, "selected item should be the default one");
-
-  await BrowserTestUtils.removeTab(gBrowser.selectedTab);
-
-  Services.prefs.clearUserPref("dom.ipc.processCount");
-  Services.prefs.clearUserPref("dom.ipc.processCount.web");
-  Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", true);
-});
-
-add_task(async function() {
-  Services.prefs.clearUserPref("dom.ipc.processCount");
-  Services.prefs.setIntPref("dom.ipc.processCount.web", DEFAULT_PROCESS_COUNT + 1);
-  Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", false);
-
-  let prefs = await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
-  is(prefs.selectedPane, "paneGeneral", "General pane was selected");
-
-  let doc = gBrowser.contentDocument;
-  let performanceSettings = doc.querySelector("#performanceSettings");
-  is(performanceSettings.hidden, false, "performance settings section is shown");
-
-  let contentProcessCount = doc.querySelector("#contentProcessCount");
-  is(contentProcessCount.disabled, false, "process count control should be enabled");
-  is(Services.prefs.getIntPref("dom.ipc.processCount"), DEFAULT_PROCESS_COUNT, "default value should be the current value");
+  is(Services.prefs.getIntPref("dom.ipc.processCount"), DEFAULT_PROCESS_COUNT, "default pref should be default value");
   is(contentProcessCount.selectedItem.value, DEFAULT_PROCESS_COUNT, "selected item should be the default one");
 
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 
   Services.prefs.clearUserPref("dom.ipc.processCount");
-  Services.prefs.clearUserPref("dom.ipc.processCount.web");
   Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", true);
 });
 
-add_task(async function() {
+add_task(async function testPrefsSetByUser() {
   Services.prefs.setIntPref("dom.ipc.processCount", DEFAULT_PROCESS_COUNT + 2);
-  Services.prefs.setIntPref("dom.ipc.processCount.web", DEFAULT_PROCESS_COUNT + 1);
   Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", false);
 
   let prefs = await openPreferencesViaOpenPreferencesAPI("paneGeneral", {leaveOpen: true});
   is(prefs.selectedPane, "paneGeneral", "General pane was selected");
 
   let doc = gBrowser.contentDocument;
   let performanceSettings = doc.querySelector("#performanceSettings");
   is(performanceSettings.hidden, false, "performance settings section is shown");
@@ -92,11 +65,10 @@ add_task(async function() {
   is(Services.prefs.getBoolPref("browser.preferences.defaultPerformanceSettings.enabled"), true,
     "pref value should be true after clicking on checkbox");
   is(Services.prefs.getIntPref("dom.ipc.processCount"), DEFAULT_PROCESS_COUNT,
     "process count should be default value");
 
   await BrowserTestUtils.removeTab(gBrowser.selectedTab);
 
   Services.prefs.clearUserPref("dom.ipc.processCount");
-  Services.prefs.clearUserPref("dom.ipc.processCount.web");
   Services.prefs.setBoolPref("browser.preferences.defaultPerformanceSettings.enabled", true);
 });