I have been working on a world for awhile with lots of stuff going on. I have found that certain areas of my world affect the speeds of a minecart. Some areas seem so bad that the minecart will pause on the tracks like a glitch or will just come to a stop even though its gone over plenty of powered rails. Whats weird is that when the minecart pauses the player does not and you can still move around. I have also tested the minecart moving with the player not in it and it still moves slow and pauses (slower than player walking/running speed). While the minecart glitches and/or pauses my player still moves (walks/runs) and does no glitch. This makes me think that the minecart rails that are programmed in the game have bugs. Can I get an explanation to why this is happening?

I also don't know the correct "Affects Version" that is asked above. 

Thanks in Advance