SQL 2000 SP4 snapshot process taking longer

I am runnung full backup on MS SQL2000 SP4 DB on daily basis.  For some reason, the sanpshot process taking way too long before it backs up the DB.  It used to take 10-11 hours to backup 10-11 hours, not it is taking 20 plus hours.  I noticed that the job gets stuck in snapshot process for a long time before it backup each DB.