As you probably know, the Slingbox's ability to stream without buffering is dependent almost entirely on a fast and consistent network connection. Your connection at home is very fast, so I'm not surprised that you would have no issues and great quality.
In times where your video is buffering a lot, the quickest way to minimize this is to adjust the quality to Standard Quality (SQ).
This article, Slingbox settings can cause poor video quality with SlingPlayer on your mobile device walks through changing this setting.
Let me know if that helps,