What is everyone doing to reduce backup windows?

I am coming from DPM and Falconstor, both do synchronizations, with timemarks (full backups at the appliance similiar to a synthetic or virtual full). I havent done a FULL backup in ages.

One of my file servers takes 10 hours, exchange 6. What is everyone doing to reduce backup times? Are synthetic or virtual fulls the way to go. We have a storeonce on the backend.

Thank you,

Theron Cooper