title: ReferenceError: performance is not defined when using performance.now()
body: <p>I am getting an error <code>ReferenceError: performance is not defined</code> when trying to use <a href="https://developer.mozilla.org/en-US/docs/Web/API/Performance/now" rel="noreferrer">performance.now()</a> to measure the execution time of a function call:</p>
  
  <pre><code>export async function find(someId: string, ctx: context.IContext) {
  
        try {
          var t0 = performance.now();
  
          var res = someModel.find(someId, ctx.cookies);
  
          var t1 = performance.now();
          console.log("Call to find took " + (t1 - t0) + " milliseconds.");
  
          return res;
        } catch (err) {
          console.error(err);
          throw err;
        }
      }
  </code></pre>
  
  <p>Any ideas how I can fix this?</p>