diff --git a/lib/plugins/filter/after_post_render/external_link.js b/lib/plugins/filter/after_post_render/external_link.js
index 10a0c0a3b2..1166636aec 100644
--- a/lib/plugins/filter/after_post_render/external_link.js
+++ b/lib/plugins/filter/after_post_render/external_link.js
@@ -1,35 +1,6 @@
 'use strict';
 
-const { URL } = require('url');
-
-const urlObj = (str) => {
-  try {
-    return new URL(str);
-  } catch (err) {
-    return str;
-  }
-};
-
-const isExternal = (url, config) => {
-  const exclude = Array.isArray(config.external_link.exclude) ? config.external_link.exclude
-    : [config.external_link.exclude];
-  const data = urlObj(url);
-  const host = data.hostname;
-  const sitehost = typeof urlObj(config.url) === 'object' ? urlObj(config.url).hostname : config.url;
-
-  if (!sitehost || typeof data === 'string') return false;
-  if (data.origin === 'null') return false;
-
-  if (exclude && exclude.length) {
-    for (const i of exclude) {
-      if (host === i) return false;
-    }
-  }
-
-  if (host !== sitehost) return true;
-
-  return false;
-};
+const { isExternalLink } = require('hexo-util');
 
 function externalLinkFilter(data) {
   const { config } = this;
@@ -46,7 +17,7 @@ function externalLinkFilter(data) {
     || config.external_link.field !== 'post') return;
 
   data.content = data.content.replace(/<a.*?(href=['"](.*?)['"]).*?>/gi, (str, hrefStr, href) => {
-    if (/target=/gi.test(str) || !isExternal(href, config)) return str;
+    if (/target=/gi.test(str) || !isExternalLink.call(this, href)) return str;
 
     if (/rel=/gi.test(str)) {
       str = str.replace(/rel="(.*?)"/gi, (relStr, rel) => {
diff --git a/lib/plugins/filter/after_render/external_link.js b/lib/plugins/filter/after_render/external_link.js
index 92ed1f57fa..e249d6c183 100644
--- a/lib/plugins/filter/after_render/external_link.js
+++ b/lib/plugins/filter/after_render/external_link.js
@@ -1,41 +1,6 @@
 'use strict';
 
-const { URL } = require('url');
-
-const urlObj = (str) => {
-  try {
-    return new URL(str);
-  } catch (err) {
-    return str;
-  }
-};
-
-/**
- * Check whether the link is external
- * @param {String} url The url to check
- * @param {Object} config The site config
- * @returns {Boolean} True if the link doesn't have protocol or link has same host with config.url
- */
-const isExternal = (url, config) => {
-  const exclude = Array.isArray(config.external_link.exclude) ? config.external_link.exclude
-    : [config.external_link.exclude];
-  const data = urlObj(url);
-  const host = data.hostname;
-  const sitehost = typeof urlObj(config.url) === 'object' ? urlObj(config.url).hostname : config.url;
-
-  if (!sitehost || typeof data === 'string') return false;
-  if (data.origin === 'null') return false;
-
-  if (exclude && exclude.length) {
-    for (const i of exclude) {
-      if (host === i) return false;
-    }
-  }
-
-  if (host !== sitehost) return true;
-
-  return false;
-};
+const { isExternalLink } = require('hexo-util');
 
 function externalLinkFilter(data) {
   const { config } = this;
@@ -52,7 +17,7 @@ function externalLinkFilter(data) {
     || config.external_link.field !== 'site') return;
 
   data = data.replace(/<a.*?(href=['"](.*?)['"]).*?>/gi, (str, hrefStr, href) => {
-    if (/target=/gi.test(str) || !isExternal(href, config)) return str;
+    if (/target=/gi.test(str) || !isExternalLink.call(this, href)) return str;
 
     if (/rel=/gi.test(str)) {
       str = str.replace(/rel="(.*?)"/gi, (relStr, rel) => {
diff --git a/package.json b/package.json
index 98eba926f9..41e8441541 100644
--- a/package.json
+++ b/package.json
@@ -45,7 +45,7 @@
     "hexo-fs": "^2.0.0",
     "hexo-i18n": "^1.0.0",
     "hexo-log": "^1.0.0",
-    "hexo-util": "^1.5.0",
+    "hexo-util": "github:sukkaw/hexo-util#perf-is-external",
     "js-yaml": "^3.12.0",
     "lodash": "^4.17.11",
     "micromatch": "^4.0.2",