ui: speed up page load

packages/ui-default/utils/base.ts

@@ -1,5 +1,7 @@
 import $ from 'jquery';
 import _ from 'lodash';
+import React from 'react';
+import DOMServer from 'react-dom/server.browser';
 
 export function substitute(str: string, obj: any) {
   return str.replace(/\{([^{}]+)\}/g, (match, key) => {
@@ -32,6 +34,7 @@ export function secureRandomString(digit = 32, dict = defaultDict) {
 type Substitution = string | number | { templateRaw: true, html: string };
 
 export function tpl(pieces: TemplateStringsArray, ...substitutions: Substitution[]) {
+  if (React.isValidElement(pieces)) return DOMServer.renderToStaticMarkup(pieces);
   let result = pieces[0];
   for (let i = 0; i < substitutions.length; ++i) {
     const subst = substitutions[i];