mainheader: call setstate only when needed for clipboard

ts/components/MainHeader.tsx

@@ -72,6 +72,7 @@ export class MainHeader extends React.Component<Props, any> {
   private readonly setFocusBound: () => void;
   private readonly inputRef: React.RefObject<HTMLInputElement>;
   private readonly debouncedSearch: (searchTerm: string) => void;
+  private readonly timerId: any;
 
   constructor(props: Props) {
     super(props);
@@ -92,9 +93,11 @@ export class MainHeader extends React.Component<Props, any> {
 
     this.debouncedSearch = debounce(this.search.bind(this), 20);
 
-    setInterval(() => {
+    this.timerId = setInterval(() => {
       const clipboardText = clipboard.readText();
-      this.setState({ clipboardText });
+      if (this.state.clipboardText !== clipboardText) {
+        this.setState({ clipboardText });
+      }
     }, 100);
   }
 
@@ -103,6 +106,11 @@ export class MainHeader extends React.Component<Props, any> {
     this.updateHasPass();
   }
 
+  public componentWillUnmount() {
+    // tslint:disable-next-line
+    clearInterval(this.timerId);
+  }
+
   public componentDidUpdate(_prevProps: Props, prevState: any) {
     if (prevState.hasPass !== this.state.hasPass) {
       this.updateMenuItems();