The problem with creating Backup

Good day.
I have at some point there was a problem with the program Acronis Backup and Recovery.
My hard drive is occupied by 8%. Previously, Acronis kept current, these 8%! And more recently he began to save the whole disk (750Gb)
And it takes a very long time!
The settings have not changed anything. How can I fix it? What would he remained current, these 8%?
And when choosing the recommended compression ratio, it decreases from 89% to 5%.