Umbracache is insanely slow to delete or copy. I used to be able to backup my project in like 1 to 2 hours. Now just because umbracache. Its 36hours +... highly inconvenient. Is there a faster way to delete these files?
Don't know what Umbracache means, but I'm guessing you're still using an old HDD if you're complaining about the amount of time it takes to do anything disk related. Get an SSD. You could also consider just moving files to another location on the same drive before doing your backup, instead of deleting. That won't actually delete them at that time, so will be pretty instantaneous. Actually delete them when you're done with your machine for the day. Lastly, use version control instead of manual backups. You shouldn't have to do any file deletions just to save your progress, which you won't when using version control.
Are they in the /Library/ folder or one of its sub folders? You should never back up that folder or add its contents to version control. The only folders you need to care about are /Assets /ProjectSetings /Packages Nothing else should be “backed up”
You can back up the Library folder, but yes, it is supposed to be something that can be completely recreated from the data in the other folders, so you shouldn't need to.