I have been playing the beta pretty thoroughly for the last week and this one bug has persisted where my movement speed will randomly come to a crawl. The speed is slower than normal movement and nothing else is slowed down and goes full speed.

The speed decrease will only last a second or so. It is most notable when trying to go backwards, and can happen in instanced content or in the open world.

I've also talked to a few others and they all experienced the same issues.