Fusion unusable slow and eating all my RAM

Hi there,
I recently purchased Davinci Studio and wanted to start doing some fancy stuff in Fusion.
Unfortunately, Fusion does not work as intended for me. If I want to play something directly in the Fusion tab, I have extremely low frame rates. At the same time, Fusion eats up my RAM. We are really just talking about playing in Fusion without effects or other nodes. If I go back to my editing timeline then I can play back what I've done in Fusion directly on the clip whitout dropped frames or I can render it there directly on the clip if it's complex. Nevertheless, an incredible amount of GPU RAM is consumed, but also the normal RAM. When I apply the effects (e.g. a LUT or Noisereduction) in the Color tab, it works flawlessly. Of course, RAM and GPU-Ram are also used, but they remain relatively constant. I've really tried a lot now. Smart cache, no cache, user cache (which I currently use to limit what I wish to have in the cache). I have put my cache on a 2TB NVME etc. I use 10bit 4:2:2 h264 and h265 files from my A7siii. The h264 files are ALL-I, so they are easier to process. Creating Proxies does not help as soon as i do anything in Fusion, and deactivating Motionblur and HIgh Quality does also not help... Just now Davinci crashed twice when I tried to render the in-house noise reduction that i added in Fusion on the timeline. It doesn't matter whether I set the Fusion-Memeorry cache activation to auto or off. it's always the same.... Am I missing something here?

I added 3 scrrenshot of my System while doing tasks in Davinci so you have a better idea of what I´m talking about.
I could also iupload a screenrecording of it if this helps....

My system:
Intel 10900k
AMD 7900XT
Water cooling
64GB 3600 DDR4 RAM

Thanks and LG
Luki

On my Apple M1 Studio Ultra 64GB, it's typical for about 40-50GB RAM to be used for Fusion compositions, often more for complex compositions.

To speed things up, use of SAVER and LOADER nodes.

First, you use a SAVER node to save the Fusion composition output in the form of fully rendered graphics files (.exr format).

Second, you use a LOADER node to import those rendered files into the node tree as already-rendered information, thus saving processing workload.

On YouTube there are quite a few tutorials on SAVER and LOADER nodes. The channel VFXstudy has a good tutorial on the topic.

I tend to use the standalone version and VFX Connect. More stable, but it still eats your RAM for breakfast.

ALL compositing apps eat RAM like there's no tomorrow.
And the more complex your comp, the more this is true

Thank you all. I think i found out 1 problem so far.
When using Fusion (in the FusionTab) in Davinci, Fusion seems not to be the biggest fan of sony H264 All-I. While being no problem on the timeline, Fusion starts to skip frames already when just playing back wihtout FX. When I´m using Proxy-Media (DNxHRQ) it plays fine. I have fusion memory chach on auto for now. it still seems to be kind of buggy and not really usable for me right now, since it still skipps frames in certain szenarios. I´ll do a screenrecording this weekend to show what i exactly mean.

best regards
lukas