Thank you for your replies. I don't need disk clean up because I am not talking about programs, I am talking about files- mostly samples (audio). I do not understand this well, but SSDs have Trim, which decides how space is allocated. There is something about how cells get filled. For example, if the cell was used but not completely filled, SSD will start writing new files on new cell and leave unfinished cell unfilled. As I say- I do not know how it works, but it leaves some space in every cell, and then if you delete small part of data, it does not go back and move all other files to fill that space. Trim is not always works correctly, so it is better to avoid recycle been at all.