From 14dd42bad05fcbb1b88b71212a1fd08dc7dd168f Mon Sep 17 00:00:00 2001
From: Rainer Simon <rainer.simon@ait.ac.at>
Date: Sun, 5 Apr 2020 18:02:18 +0200
Subject: [PATCH] Performance tweak

---
 src/highlighter/Highlighter.js | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/highlighter/Highlighter.js b/src/highlighter/Highlighter.js
index faee30b..1a31d1a 100644
--- a/src/highlighter/Highlighter.js
+++ b/src/highlighter/Highlighter.js
@@ -11,13 +11,14 @@ export default class Highlighter {
     this.formatter = formatter;
   }
 
-  init = annotations => {
-    // TODO - there are several performance optimzations that are not yet ported
-    // across from Recogito
-    annotations 
-      // Discard all annotations without a TextPositionSelector
-      .filter(annotation => annotation.selector('TextPositionSelector'))
-      .forEach(annotation => this._addAnnotation(annotation));
+  init = annotations => {    
+    // Discard all annotations without a TextPositionSelector
+    const highlights = annotations.filter(a => a.selector('TextPositionSelector'));
+
+    // Sorting bottom to top significantly speeds things up,
+    // because walkTextNodes will have a lot less to walk 
+    highlights.sort((a, b) => b.start - a.start);
+    highlights.forEach(this._addAnnotation);
   }
 
   _addAnnotation = annotation => {