You may experience jitters during audio streaming if the WiFi signal quality is bad, or if the reception is inadequate. You need 3 bars or better of WiFi signal to experience jitter free audio streaming.
You may also be experiencing jitters if your router is running an old firmware. Visit the router manufacturer’s website to download and install the latest firmware. In most cases, this resolves jitter and lag related issues.
If none of these tips resolve your issue, and your computer is equipped with a strong WiFi signal, try setting up an ad-hoc connection between your computer and your iOS device to rule out any router-related issues.