It's happening a couple of days, have a mavic pro, after the first battery charge everything works great, but when I change the battery to the second one I have, the video transmission becomes very slow, that it's practically impossible to control my mavic, I have to land  it by sight, any help?  

Is it always the same battery that appears to cause the problem? Check and see if all your batteries have had their firmware updated.

Are you on Android or iPhone?