diff --git a/src/webui/www/private/scripts/file-tree.js b/src/webui/www/private/scripts/file-tree.js
index 3622b5842..328806988 100644
--- a/src/webui/www/private/scripts/file-tree.js
+++ b/src/webui/www/private/scripts/file-tree.js
@@ -72,14 +72,17 @@ window.qBittorrent.FileTree ??= (() => {
             return this.root;
         },
 
-        generateNodeMap: function(node) {
-            // don't store root node in map
-            if (node.root !== null)
-                this.nodeMap[node.rowId] = node;
+        generateNodeMap: function(root) {
+            const stack = [root];
+            while (stack.length > 0) {
+                const node = stack.pop();
 
-            node.children.each((child) => {
-                this.generateNodeMap(child);
-            });
+                // don't store root node in map
+                if (node.root !== null)
+                    this.nodeMap[node.rowId] = node;
+
+                stack.push(...node.children);
+            }
         },
 
         getNode: function(rowId) {
@@ -93,21 +96,17 @@ window.qBittorrent.FileTree ??= (() => {
         },
 
         /**
-         * Returns the nodes in dfs order
+         * Returns the nodes in DFS in-order
          */
         toArray: function() {
-            const nodes = [];
-            this.root.children.each((node) => {
-                this._getArrayOfNodes(node, nodes);
-            });
-            return nodes;
-        },
-
-        _getArrayOfNodes: function(node, array) {
-            array.push(node);
-            node.children.each((child) => {
-                this._getArrayOfNodes(child, array);
-            });
+            const ret = [];
+            const stack = this.root.children.toReversed();
+            while (stack.length > 0) {
+                const node = stack.pop();
+                ret.push(node);
+                stack.push(...node.children.toReversed());
+            }
+            return ret;
         }
     });
 
@@ -140,55 +139,68 @@ window.qBittorrent.FileTree ??= (() => {
             this.isFolder = true;
         },
 
-        addChild(node) {
+        addChild: function(node) {
             this.children.push(node);
         },
 
         /**
-         * Recursively calculate size of node and its children
+         * Calculate size of node and its children
          */
         calculateSize: function() {
-            let size = 0;
-            let remaining = 0;
-            let progress = 0;
-            let availability = 0;
-            let checked = TriState.Unchecked;
-            let priority = FilePriority.Normal;
+            const stack = [this];
+            const visited = [];
 
-            let isFirstFile = true;
+            while (stack.length > 0) {
+                const root = stack.at(-1);
 
-            this.children.each((node) => {
-                if (node.isFolder)
-                    node.calculateSize();
+                if (root.isFolder) {
+                    if (visited.at(-1) !== root) {
+                        visited.push(root);
+                        stack.push(...root.children);
+                        continue;
+                    }
 
-                size += node.size;
+                    visited.pop();
 
-                if (isFirstFile) {
-                    priority = node.priority;
-                    checked = node.checked;
-                    isFirstFile = false;
-                }
-                else {
-                    if (priority !== node.priority)
-                        priority = FilePriority.Mixed;
-                    if (checked !== node.checked)
-                        checked = TriState.Partial;
+                    // process children
+                    root.size = 0;
+                    root.remaining = 0;
+                    root.progress = 0;
+                    root.availability = 0;
+                    root.checked = TriState.Unchecked;
+                    root.priority = FilePriority.Normal;
+                    let isFirstFile = true;
+
+                    for (const child of root.children) {
+                        root.size += child.size;
+
+                        if (isFirstFile) {
+                            root.priority = child.priority;
+                            root.checked = child.checked;
+                            isFirstFile = false;
+                        }
+                        else {
+                            if (root.priority !== child.priority)
+                                root.priority = FilePriority.Mixed;
+                            if (root.checked !== child.checked)
+                                root.checked = TriState.Partial;
+                        }
+
+                        const isIgnored = (child.priority === FilePriority.Ignored);
+                        if (!isIgnored) {
+                            root.remaining += child.remaining;
+                            root.progress += (child.progress * child.size);
+                            root.availability += (child.availability * child.size);
+                        }
+                    }
+
+                    root.checked = root.autoCheckFolders ? root.checked : TriState.Checked;
+                    root.progress /= root.size;
+                    root.availability /= root.size;
                 }
 
-                const isIgnored = (node.priority === FilePriority.Ignored);
-                if (!isIgnored) {
-                    remaining += node.remaining;
-                    progress += (node.progress * node.size);
-                    availability += (node.availability * node.size);
-                }
-            });
-
-            this.size = size;
-            this.remaining = remaining;
-            this.checked = this.autoCheckFolders ? checked : TriState.Checked;
-            this.progress = (progress / size);
-            this.priority = priority;
-            this.availability = (availability / size);
+                stack.pop();
+            }
         }
     });