Memory consumption

Hello, I have been using Backwpup on many sites for a long time and have found it fantastic, but I have one site where, when backing up the whole site (about 500MB), the physical memory use according to CPanel is over 2GB at its peak, and then remains at over 900MB for about 5-10 minutes even after the backup is complete. Is this normal and is there anything I can do to reduce the strain? Thank you.