RESOLVE 12 Constant Disk Useage

I've been playing around with 12 and it looks pretty good but one issue I'm having is it is continually accessing my RAID and killing disk performance. I went through every setting in the entire program to turn off caching and optimized media and if a disk path was in the menu I set it to another disk but as long as Resolve is running my RAID is going non stop. The RAW footage is on the RAID. As soon as I quit Resolve, disk activity goes to nothing. What is it doing?

I just wanted to add this is 4K FS7 footage on a Mac Pro 10.10.4 GTX 980. I might try to convert to ProRes and see if it's still doing this.

Is it optimizing media?

I turned that off but it's still doing something. Also I notice Resolve kind of craps out after a while with 4K. I've got a 6GB GPU and 64GB system ram but I start getting beachballs and delays and it gets unusable until I restart Resolve. It does seem to be better allowing Resolve to transcode the media but there still is a lot of extra activity going on that's bogging it. Pretty simple timeline, just grading 15 or so 4KUHD shots.

Start a new project? Reinstall?