Spotting the bottle neck

[Hakol.Sound]

I have some heavy load Arena projects- > 8K comp, >30 layers, many FX, many live cams in, all of it are running on a fixed 50fps with generally great success.
Trying to intentionally overload the machines with more FX, more textures and more layes, I can see the FPS drops whiles the card temp and utilisation stays at under 45% capacity and below 65deg, which is not near the cards capabilities. CPU is also way under 15% and memory usage is the same.

The machine i'm testing has 256GB ram, RTX 6000 ada and if feels like we're not at the tip of the iceberg in terms of over-use.

With that in mind, where is the bottle neck that slows down the process and make FPS drop?
Thanks!

[Zoltán]

Could be texture transfers from/to the GPU.

[Hakol.Sound]

How can it get improved?