perf: add eventbus unmount in more places and optimise stats tab

src/components/widgets/background/Background.jsx

@@ -355,6 +355,10 @@ export default class Background extends PureComponent {
     this.setBackground();
   }
 
+  componentWillUnmount() {
+    EventBus.off('refresh');
+  }
+
   render() {
     if (this.state.video === true) {
       const enabled = (setting) => {

src/components/widgets/greeting/Greeting.jsx

@@ -134,7 +134,7 @@ export default class Greeting extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/quicklinks/QuickLinks.jsx

@@ -131,7 +131,7 @@ export default class QuickLinks extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/quote/Quote.jsx

@@ -247,7 +247,7 @@ export default class Quote extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/search/Search.jsx

@@ -126,7 +126,7 @@ export default class Search extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/time/Clock.jsx

@@ -114,7 +114,7 @@ export default class Clock extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/time/Date.jsx

@@ -128,7 +128,7 @@ export default class DateWidget extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {

src/components/widgets/weather/Weather.jsx

@@ -125,7 +125,7 @@ export default class Weather extends PureComponent {
   }
 
   componentWillUnmount() {
-    EventBus.remove('refresh');
+    EventBus.off('refresh');
   }
 
   render() {