At its core, the Chromecast is essentially a web browser on a stick. When you cast content from your computer or smartphone, all you're really doing is telling the Chromecast which website to load.
So if you're experiencing lag or issues casting content, the root cause is generally network related. But while there are many tools to help diagnose such issues on all of our other devices, the Chromecast has never had such a utility—until now, that is.
The development team at Yu Tao Software has created an Android app that will perform a network diagnostic test on your Chromecast. While this isn't a one-click fix by any means, the info it yields will at least get you on the right path in troubleshooting network issues on your Chromecast.
Yu Tao's app is available for free on the Google Play Store. Search Speed4Cast to get it installed, or head directly to the install page here.
Speed4Cast has a simple and intuitive interface. Tap the "Cast" icon at the top of the screen, then select your Chromecast or Google Cast-compatible device to begin.
When you see the Speed4Cast interface appear on your TV, tap the big pink button to run your network diagnostics test.
Speed4Cast will run its diagnostics on your Chromecast, and you'll see the results on your television. The app makes multiple passes to ensure accurate results, so the process will take up to a minute to complete.
When the test is complete, you'll see the results on the right half of your screen. Metrics include latency, jitter, upload and download speeds, and even your Chromecast's outbound IP address.
While this may not fix connection issues with your Chromecast directly, you now have a great starting point in troubleshooting. If one of your numbers looks way off, you can Google "Chromecast high latency," for instance.