That ram preview is not realtime guaranteed as it used to be up to the cc-version was a hard pill to swallow especially since this should be one of the basic features of an animation program, but I guess it is more important that we all can hold hands via social media now about keyframes and all our projects in the cloud as if anyone would have wanted that to happen.
But anyway: there used to be the feature, that if you hit "Num - Zero (0)" twice while ram preview was caching you would get the chance to see your ram-preview before it rendered entirely to the end of the work area. Which was a very thoughtful feature, since you DO NOT want to adjust your workspace everytime you want to see something new... but this feature is gone now since AE2020 if I call correctly... by the way adobe: how about Calling After Effects 2021 After Effects V18? So people dont get confused and have to look up everytime the corresponding version.
I sometimes wonder whats going on over there... the program seems to get worse. Core features are being messed with. OG Animators like myself are disappointed about this lack of selfconsciousness on Adobes side. And do believe, I am not alone on this. Lets make AE realtime again. And bring back the double Zero. Thank you!
Error or problem, Freeze or hang, Performance, Preview