My Passport 4TB slow read/write performance

Hi,

I bought a WD My Passport 4TB very recently and after starting to copying some files to it and read from it I realized that the speed of read/write is very slow. I ran some benchmarks on it while it is half full, the performance is really disappointing.

The speed of read/write never passed 5mb/s and in some cases with smaller file sizes it is 1mb/s, is this normal for a 4TB USB 3 that is the only disk plugged to the computer?