Had no issues using Movie Maker (2012 Build 16.4.3522.0110) until the other day with the purchase of a new Panasonic video camera.

When trying to edit the AVCHD (.MTS) files the editor is very slow, the preview play/pause button and the timeline marker take several seconds to do anything. Selecting Animations causes similar delays. When editing .MP4 files from my GoPro 3 it is super slick, i can move the timeline marker around with little or no lag.

If i try the same files on my other PC which is using Movie Maker 2011 (Build 14.4.3538.0513) the MTS files work without issue.

Has anyone else seen this problem?