I have noticed a lot of lip burrs on the ends of the rails on each track section. You can feel and hear that lip well when your train runs over them. I took each track and de-burred the ends using a metal fingernail file. Train runs alot smoother now over the connections.
that should be standard procedure for any track, regardless of who made it. you will find a small jewelers file does a better job of knocking the burrs off than a fingernail file.