Miracast is a peer-to-peer wireless connection to your HDTV. You can use a third party dongle or some newer HDTV's have built-in support. SHIELD has Miracast support built-in.
This technology may introduce latency which can become noticeable in some games. If you are having latency issues when streaming from SHIELD to an HDTV via Miracast, try the following steps:
1) On your SHIELD, make sure "Game Mode" is enabled in the Miracast settings menu.
2) Check whether your HDTV has a Game mode or Game setting. Some HDTVs do a lot of image processing which can add significant latency and also may add a lot of input buffering which is fine for movies but adds latency for games.
3) Many Wi-Fi routers support both 2.4gHz and 5gHz channels. SHIELD will use the same channel for Miracast as it uses for the connection to your Wi-Fi router or Access Point (AP). If possible, setup your router so that SHIELD can connect at 5gHz. This will allow the Miracast connection to also be 5gHz which tends to result in lower latency. Each Wi-Fi router is different, consult your Wi-Fi router owner's manual for details.
4) Some games just need more video bandwidth while also being more latency sensitive. Try a few different games and see if some perform better than others.