diff --git a/builder/doc.html b/builder/doc.html
index 9b735e8..0a52469 100644
--- a/builder/doc.html
+++ b/builder/doc.html
@@ -1376,6 +1376,7 @@
     <script type="text/javascript" src="../js/utils.js"></script>
     <script type="text/javascript" src="../js/build_utils.js"></script>
     <script type="text/javascript" src="../js/computation_graph.js"></script>
+    <script type="text/javascript">COMPUTE_GRAPH_DEBUG=true;</script>
     <!-- <script type="text/javascript" src="../js/icons.js"></script> -->
     <script type="text/javascript" src="../js/sq2icons.js"></script>
     <script type="text/javascript" src="../js/powders.js"></script>
diff --git a/js/computation_graph.js b/js/computation_graph.js
index 0dcc8d8..d144e29 100644
--- a/js/computation_graph.js
+++ b/js/computation_graph.js
@@ -1,5 +1,6 @@
-let all_nodes = [];
+let all_nodes = new Set();
 let node_debug_stack = [];
+let COMPUTE_GRAPH_DEBUG = false;
 class ComputeNode {
     /**
      * Make a generic compute node.
@@ -21,7 +22,7 @@ class ComputeNode {
                                 // 0: clean
         this.inputs_dirty = new Map();
         this.inputs_dirty_count = 0;
-        all_nodes.push(this);
+        if (COMPUTE_GRAPH_DEBUG) { all_nodes.add(this); }
     }
 
     /**
@@ -34,7 +35,7 @@ class ComputeNode {
         if (this.dirty === 0) {
             return;
         }
-        node_debug_stack.push(this.name);
+        if (COMPUTE_GRAPH_DEBUG) { node_debug_stack.push(this.name); }
         if (this.dirty == 2) {
             let calc_inputs = new Map();
             for (const input of this.inputs) {
@@ -46,7 +47,7 @@ class ComputeNode {
         for (const child of this.children) {
             child.mark_input_clean(this.name, this.value);
         }
-        node_debug_stack.pop();
+        if (COMPUTE_GRAPH_DEBUG) { node_debug_stack.pop(); }
         return this;
     }
 
@@ -190,7 +191,7 @@ function calcSchedule(node, timeout) {
     }
     node.mark_dirty();
     node.update_task = setTimeout(function() {
-        node_debug_stack = [];
+        if (COMPUTE_GRAPH_DEBUG) { node_debug_stack = []; }
         node.update();
         node.update_task = null;
     }, timeout);