Minor perf tweaks

src/components/d-figure.js

@@ -87,12 +87,14 @@ export class Figure extends HTMLElement {
   addEventListener(eventName, callback) {
     super.addEventListener(eventName, callback);
     // if we had already dispatched something while presumingly no one was listening, we do so again
-    if (this._ready && eventName === 'ready') {
-      this.ready();
-    }
-    if (this._onscreen && eventName === 'onscreen') {
-      this.onscreen();
-    }
+    setTimeout(() => {
+      if (this._ready && eventName === 'ready') {
+        this.ready();
+      }
+      if (this._onscreen && eventName === 'onscreen') {
+        this.onscreen();
+      }
+    }, 1);
   }
 
   // Custom Events

src/components/d-front-matter.js

@@ -19,10 +19,14 @@ export class FrontMatter extends HTMLElement {
   constructor() {
     super();
 
-    const options = {childList: true, characterData: true, subtree: true};
-    const observer = new MutationObserver( () => {
-      const data = parseFrontmatter(this);
-      this.notify(data);
+    const options = {childList: true};
+    const observer = new MutationObserver( (entries) => {
+      for (const entry of entries) {
+        if (entry.target.nodeName === 'SCRIPT') {
+          const data = parseFrontmatter(this);
+          this.notify(data);
+        }
+      }
     });
     observer.observe(this, options);
   }