diff --git a/packages/@vuepress/core/lib/client/redirect.js b/packages/@vuepress/core/lib/client/redirect.js
index 3f59573961..7e10b69a8c 100644
--- a/packages/@vuepress/core/lib/client/redirect.js
+++ b/packages/@vuepress/core/lib/client/redirect.js
@@ -50,5 +50,6 @@ export function handleRedirectForCleanUrls (router) {
 }
 
 function isRouteExists (router, path) {
-  return router.options.routes.filter(route => route.path.toLowerCase() === path.toLowerCase()).length > 0
+  const pathLower = path.toLowerCase()
+  return router.options.routes.some(route => route.path.toLowerCase() === pathLower)
 }