PCG, Virtual Textures, Landscape

Hello! So first of Im running a Intel i7 coffe lake , 32gb ram, rtx 3090 12gb vram, nvme hdd & ssd.
When Im trying to make a landscape in 5.4.2 and add a landscape material is crashes, got errors about RHI and that im out of video memory, how much do I really need? And it wasn’t a heightmap only flat 8k .

Also, when merging my project from 5.3 I get really bad frames when activating PCG graphs, from around 40 to 19fps. And the virtual textures are blurry, getting the message that it’s resizing, I used own pools but my vegetation is still blurry, and even if I uncheck the auto size I still have blurry textures… and ideas? I don’t understand why the performance is so bad…