Need to inspect Application Server backups and status

Our application running on Java and MongoDB has three server instances running. One of the three goes into interruptible sleep/Waiting for event to complete (man page process state code S+) from Running (man page process state code R+). This switch is affecting the speed and accessibility of the app, making it stop for multiple hours on end. We believe this is happening due to database backups. Want someone to inspect this and change the same.