Preview playback slows after a minute of working in AE

[Guest]

Hello,
I have this issue that I cant figure out no matter what I try and that has been persistent on multiple different machines that I have used so I would really appreciate if someone could give me some advice on what to do here.

What I am working with:
I have a 13 minute video sequence that I have assembled in Premier. The original footage is 1920x1080 29.97fps. Knowing that After Effects is always very laggy I learnt that it might be a good idea to create proxies, - and so that is what I did. The proxies for all of the clips are - 1024x540. What I usually do after is I select all of the clips in Premier and paste them to After Effects inside of the "Main" comp. It then automatically has all of the clips inside of AE with linked proxies.

What the issue is:

Now, the proxies inside of AE are enabled (I make sure that the square box is ticked) and I proceed to create animations wherever I see necessary. Some 2D infographics here and there but nothing super complicated. Although in the beginning the playback is alright soon after, usually when I come back to work on the project the next day, the playback is in slow motion even for the parts where there is no animations at all. The cache preview line is fully green but the footage doesnt play in real time. It plays at 6 fps according to info. I have allocated 52 gb of ram to AE. I purge cache it works fine for a few moments, the playback is in real time and then it slows down again to a crawl. Same thing happens when I restart the software it works fine for 20-30 seconds and then slows down again.

WHY IS THIS HAPPENING?



System Specs:
64gb RAM
AMD Ryzen 7 3700X
Radeon RX 570 Series 8gb

AE Version: 23.1

[Warren Heaton · Accepted solution]

After Effects treats everything as if it is uncompressed (which is ideal for motion graphics and visual effects).

If your project is set to 8 bits per channel, a 1920-by-1080 Composition is about 8MB per frame.  With a duration of 13 minutes, After Effects is being asked to process a significant amount of data over 13 minutes, not including any overhead for whatever Masks, Effects, and Transforms are being applied.  

Try breaking your 13-minute project into separate Comps based on shots or scenes.

For timing, use a low Comp Resolution (Quarter usually works well).

Try to work from fast SSD drives if not doing so already.

[Guest]

Aha... Now I understand. I already use fast SSD and just couldn't figure out what the issue was. It turns out the workflow itself was flawed. Thank you for the advice. It seems to solve the issue completely.