So. After about 1sec of "normal" preview my preview gets extremely slow sometimes stopping completely for about 3-5sec, even though the preview resolution is 1/8 of the composition and the Framerate is set to skip 5 frames.
My hardware shouldnt be a problem. I have a Ryzen 7 3700x, a RTX2080, 32GB of 3200MHz RAM and a really fast PCIe 3.0 SSD. When previewing the RAM usage gets out of control quickly but even when the Ram is not full the preview lags.
The usual applies: Those are issues with leaky drivers and you can't fix them from within Ae by pushing a magic button or whatever you imagine. You have to sit down and configure your hardware correctly such as updating your graphics driver/ installing a different version and playing around with settings.