Hi Firezown,
Are you using a starting template with this setup or are you using your own created from scratch setup? Depending how your movement is setup could be the issue. If the movement is following where the camera looks this could be why the movement is slowing like this.
This was actually an issue with our first person template in 4.1 and before. This was fixed with release of 4.2.
You can take a look at the MyCharacter controller setup for these and see if this resolves your issue.
Let me know how it goes! 
Tim