Node Cache stopped working mid-project.

Created a new project and suddenly the Node caching in the Color page stopped working and DV response time is crazy slow on a beefed up Mac Pro.

Normally I cache fx. a Noise Reduction node, by right-clicking selecting "Node Cache" > On.
The node goes from red to blue when the caching is done. But suddenly this stopped working.
I can not force the nodes to cache and they stay red (non-cached).

And the response time of everything else has also gone haywire. Turning a simple node on/off takes 15 sec. to be shown on screen. Pressing Play takes 15 sec. to take effect.

I've tried rebooting, restarting, switching node caching to Auto/On/Off, changing Playback>Render Cache>None/Smart/User. But nothing helps and it's not possible to work.

If I go Activity Monitor I see that Davinci uses 2-300% of the CPU so it must be stuck doing someting, but it's been like that for hours.


Set up:
I have the exact same settings as other timelines that worked fine.
Footage is Canon RAW 4096x2160
Timeline: 4096 x 2160 DCI - DaVinci YRGB Color Managed - DaVinci Wide Gamut

DV 17.1.1 Build 9
macOS 11.2.3 Big Sur
Mac Pro 7.1 - 16-core, 256GB RAM
GPU: AMD Radeon Pro Vega II 32GB

UPDATE: SOLVED.

I had a "Deflicker" node at the end of the node tree. After deleting that, resetting the node tree and starting grading over again, everything is back to normal.

Perhaps anyone here knows if that's whats to be expected of a Deflicker node? What it normal procedure with those - should a deflicker come first or last in a node tree - if it matters at all?

i rarely have to cache anything, but Deflicker is cached always - it's super resource intensive
i put it at the end of the tree, it's not a free lunch and can soften an image significantly... at the end of the pipeline i can use best judgment to use the least amount needed, and mask what is not effected by the flicker

Thanks Dermot.

Makes total sense to window out what is not need in my case as the flicker was only visible in 25% of the frame. Thanks for the tip.

And I had no idea Deflicker was so CPU intensive it could take my machine down, which I consider to be pretty powerful. But guess you can never have enough of anything when it comes to hardware