many changes related to #1192:

- use CSS contain wherever possible to reduce subtrees of forced reflows
- reduced dependency between note and note_contents updates which will reduce number of updates to components
- optimization of "many rows" querying

src/public/app/widgets/collapsible_widget.js

@@ -29,6 +29,7 @@ export default class CollapsibleWidget extends TabAwareWidget {
 
     doRender() {
         this.$widget = $(WIDGET_TPL);
+        this.contentSized();
         this.$widget.find('[data-target]').attr('data-target', "#" + this.componentId);
 
         this.$bodyWrapper = this.$widget.find('.body-wrapper');