diff --git a/src/core/render/compiler.js b/src/core/render/compiler.js
index fbc3f083c..78250f257 100644
--- a/src/core/render/compiler.js
+++ b/src/core/render/compiler.js
@@ -106,8 +106,9 @@ export function sidebar (text, level) {
     html = markdown(text)
     html = html.match(/<ul[^>]*>([\s\S]+)<\/ul>/g)[0]
   } else {
-    const tree = genTree(toc, level)
+    const tree = cacheTree[currentPath] || genTree(toc, level)
     html = treeTpl(tree, '<ul>')
+    cacheTree[currentPath] = tree
   }
 
   return html
diff --git a/src/core/render/index.js b/src/core/render/index.js
index d6b689336..de7a6fa28 100644
--- a/src/core/render/index.js
+++ b/src/core/render/index.js
@@ -75,7 +75,7 @@ export function renderMixin (proto) {
 
     this._renderTo('.sidebar-nav', sidebar(text, maxLevel))
     const active = getAndActive('.sidebar-nav', true, true)
-    loadSidebar && subSidebar(active, subMaxLevel)
+    subSidebar(loadSidebar ? active : '', subMaxLevel)
     // bind event
     this.activeLink = active
     scrollActiveSidebar()