framerate

Hello Eliya2349454152iv,

Can you please check with your AE settings. (Go to Preferences > Previews)

If these suggestions don't help you with your concern, please post your machine specs, it will help us to resolve your issue.

Thank you.

Hi Eliya2349454152iv,

I agree with what the experts suggested. Here's an article with more details on how After Effects work when it comes to previewing: https://community.adobe.com/t5/after-effects-discussions/faq-why-doesn-t-after-effects-preview-in-real-time-like-premiere-pro/td-p/10690804

Let us know if there are any other questions.

Thanks,

Nishu

My first guess is that your RAM is being filled up, so it's limiting the amount of your timeline being previewed. At 30fps, you've got about 3.5 times as many frames needing to be processed, compared to 8fps. 

Go to Edit > Purge > All Memory and Disk Cache. Try building a new preview. Still having the issue?

There are ways to speed up previews (and save the necessary RAM space) by adjusting settings in the Preview panel, like Skip and Resolution. Give those a shot. 

If these suggestions don't help, please post your machine specs and some screenshots of your project, so we can further assess.

I would guess this has to with your systems available meory and or cahe space.

rendering 30fps for 20 seconds will logically take up more system resources than 8fps for 20 seconds.