It is basically because Euckaryotic cells are more complex than Bacteria, thus more stages are to be completed when it comes to DNA and Molecular Genetics dynamics.
Eukayotes carry membrane-bound organelles and a nucleus whether they are single celled or multi cellular organisms. In Bacteria on the other hand membrane-bound organelles and/or nucleus are not available; making them simpler organisms; so when the DNA replication process happens it's easier to produce a replica of a Bacteria than it is for an Eukariotic cell.
