Fusion tab playback not smooth

Hi all,
I'm new to using Fusion'tab in Resolve 18.5

I cant find the way to get a smooth playback in Fusion's tab.
My footage are 4k and my PC is fast (SSD, 128Go ram, threadripper, 2xRTX3090).

I need to work on precise selection so I cant use proxy (that blurs the image).
I turned off motion blur and HiQ, and the cache is set to smart.
Although when I playback it's never smooth, sometime the thin line above the timeline turms green
but playback is still a few fps but never 24 fps.

What am I miising please?

If the node has a green line then it should be saved to RAM and play back in real time. Unfortunately the behavior of still having choppy playback is happening for some time now.

Sometimes it helps to disable the GPU processing on certain nodes. Especially Merge nodes. Sometimes it also helps to purge the memory and render it again. It’s mostly about freeing VRAM.

In rare cases Fusion also has issues with certain nodes forcing a re render on each frame despite them being in RAM supposedly. But that will also clear the green line.

The only way of reliably fixing it, at least for some time, is restarting the application. This isn’t really a good workaround.
I hope more people see this post and someone might have a better solution.
Maybe even contact support.

Thanks...that's what I was affraid of : bad ram reading.

It restarted Resolve (and the PC) and it's all the same
and the Ram is only filled at 9%.

I switched back to Fusion standalone wich works perfectly well.

In rare cases Fusion also has issues with certain nodes forcing a re render on each frame despite them being in RAM supposedly. But that will also clear the green line.

The only way of reliably fixing it, at least for some time, is restarting the application. This isn’t really a good workaround.

For some time now, the RAM cache hasn't been functioning properly. There is useless re-rendering frequently. The last node is all green, but when I hit the render button, Fusion doesn't use it.

But I can't report it because it's random.

My case is Fusion Studio.

Yeah, been an issue for a few years at least. Lots of reports, but it can't be reproduced since a restart fixes it (but of course you lost all your cached frames).

Likelihood of it happening seems to relate to the complexity of comps. But that might just be the likelihood of me being frustrated by it.

This happens even in simple comps with less than 10 nodes. You just don't care because the re-calculation is so fast.