diff --git a/src/index.js b/src/index.js
index 565ccaa..cd3faa5 100644
--- a/src/index.js
+++ b/src/index.js
@@ -55,6 +55,13 @@ interface Feature {
 */
 export const FEATURE: Feature = {};
 
+/**
+* The runtime's performance API.
+*/
+interface Performance {
+    now(): number;
+}
+
 /**
 * Represents the core APIs of the runtime environment.
 */
@@ -76,6 +83,15 @@ interface Platform {
   */
   history: Object;
   /**
+  * The runtime's performance API
+  */
+  performance: Performance;
+  /**
+  * Registers a function to call when the system is ready to update (repaint) the display.
+  * @param callback The function to call.
+  */
+  requestAnimationFrame(callback: (animationFrameStart: number) => void): number;
+  /**
   * The runtime's XMLHttpRequest API.
   */
   XMLHttpRequest: XMLHttpRequest;