A big problem with songs on xdj 1000

I have a problem with xdj 1000 mk1 players.

The flash memory that I use is sandisk ultra fit 128 gb 3.0. The size of the music library is about 90 gb (all songs are in mp3 "CBR" format), of course the mp3 library is analyzed in the recordbox.

Let's get to the problem:

1. Load the song to the player takes a long time. I often see the message "now loading".

2. I can not scroll the song smoothly (scrolling is done by jumping on the track), when I release the button from the scroll, the player wonders where he is (he does not play the song immediately).

The problem occurs on most tracks but not on all of them.

I thought it was a flash memory problem and I checked the library on a portable hard drive. This problem also occurs but the waiting time is slightly smaller.

Please help me what to do in this case.