The transactions are free if you send from a Tether.to wallet to another Tether.to wallet or a Tether-enabled blockchain wallet. Everything outside is charged with a fee. Cryptopia, for example, is charging 5 USDT per withdraw.
Also, the transaction time is related to Bitcoin because the fee is paid in BTC.
Perhaps XDG can be a solution for you if you're looking for a low cost TX fee
Thanks for the answer, so tether to tether are free. I'm looking for low Tx fee but mostly speed of execution. Can't seem to find XDG on CMC, you mean DOGE? Care to point me out to their project website please if it aint DOGE.