⚡ cache the bounded function in sandbox

src/sandbox.ts

@@ -65,6 +65,7 @@ export function genSandbox(appName: string) {
   let renderSandboxSnapshot: Map<PropertyKey, any> | null = null;
   let inAppSandbox = true;
 
+  const boundValueSymbol = Symbol('bound value');
   const sandbox = new Proxy(window, {
 
     set(target: Window, p: PropertyKey, value: any): boolean {
@@ -101,9 +102,14 @@ export function genSandbox(appName: string) {
       @warning 这里不要随意替换成别的判断方式，因为可能触发一些 edge case（比如在 lodash.isFunction 在 iframe 上下文中可能由于调用了 top window 对象触发的安全异常）
        */
       if (typeof value === 'function' && !isConstructable(value)) {
+        if (value[boundValueSymbol]) {
+          return value[boundValueSymbol];
+        }
+
         const boundValue = value.bind(target);
         // some callable function has custom fields, we need to copy the enumerable props to boundValue. such as moment function.
         Object.keys(value).forEach(key => boundValue[key] = value[key]);
+        Object.defineProperty(value, boundValueSymbol, { enumerable: false, value: boundValue });
         return boundValue;
       }