Playback skips and plays frames slowly with new audio? I have a video in 1080p and inserted audio. When I play this back, the video preview window is lagging and skipping frames. The audio however sounds normal. This problem does not happen when I only play the initial audio. 

My computer has not had this problem when I previously replaced the audio in Blender and I tried restarting my computer with the same problems.
Make sure that you have enabled AV Sync in the timeline window (different from VSE window)



This will tell Blender to skip video frames in order to play at the project frame rate.