You could try to use some sort of zip utility to combine all the files and directory structure into a single file. This will still take up time and resources on the system but it would make backups much quicker. There are better ideas, though.
NetBackup has a relatively new feature called Accelerator that might be able to use if you have NBU appliances or a vendor who supports this through OST. This is good for low change rate scenarios.
VADP would allow you to do a snapshot backup of the entire VM with NetBackup, this would be much faster. There are other requirements, but it definitely would work well.
Flashbackup may take just as long as it has to backup the entire raw device, including any blank space on the filesystem, but it would also work.
Another consideration would be for Synthetic Backups. You would still lose a lot of time as the filesystem reads the files to be backed up and compares any changes. This is good for low change rate scenarios.
I believe all of these will require a license to enable and they may require testing to see which one works best in your situation.
I hope that helps,