This is gps software (and navi hardware) discussion forum
Tab3 is tablet from the lower segment (price and quality). Of course it is much slower then Galaxy S4.
If your primary use for navigation only, buy cheapest available at your market. If you want really good device, then buy new TAB S2, [Only registered and activated users can see links. ] . It is 8" but much comfortable for work and a hell of machine.
If you insist @ 7", then something like Tab4, or Nexus 7, or LG G Pad, or ASUS Memo Pad 7, or....The choice is very wide, the money is all yours, the taste too. Read reviews on the net, if you have the opportunity take them into the hands, play with them a few minutes...
Questions of this type are very ungrateful, advice also, so please, avoid them in this forum.