I've been playing around with the Hololens vuforia samples. I've used Vuforia extensively for Android and even on the Moverio BT-200 platform.
The Hololens versions does a pretty intelligent thing in that it anchors the models to the Hololens environment to help with tracking. If the image marker doesn't move it tracks perfectly. (It has to be pointed out that if you have a model in Hololens without any marker it still tracks perfectly because the Hololens' environment tracking is so robust.)
If the image marker moves however, the performance is terrible. The tracking is very laggy and imprecise even on the official sample with a full page sized marker.
The confusing part to me is that the Android version, using hardware that is clearly not as robust, was able to track much better without the degree of lag and imprecision we see on the Hololens version. Is there are reason for this? The degree of poor performance was very surprising to me.