If the camera can still be panned during the stutter, then it’s a freezing bug that was reported a long time ago (I’m doing research).
Edit: Ok, I found a video from end of November that shows a complete freezing of the game (except the camera, and it wasn’t due to pathfinding). Here it’s mentioned some possible causes for this kind of situations.
On the other hand, there’s this report here which was merged to a memory leak bug, but it’s slightly similar to our stutter.
This quote is a proof of my guesses (when the Vista bug was resolved):
The fact that some people experience the stutter when moving the camera, makes me think that the cursor didn’t detect a valid panning surface, but people who can move the camera while the game is freezed make me think we’re talking about different bugs.
In conclusion, I think this needs further investigation, so we should try reproducing and recording this new stutter of Alpha 7.