After Effects 2025 preview lag (need help)

Hi simo_naim_0374,

Thanks for reaching out. After Effects preview works differently compared to an NLE like Premiere Pro. After Effects needs to first create cache for each frame (indicated by the green line) and store them in RAM. Only then can it preview in real time. I see After Effects caching frames in the screen recording you shared. It should preview all the cached frames in real-time.

Hope it helps. Moving this thread from Bugs to Discussions for troubleshooting.

Hi, 

I think it's hard to tell, why you lack performance without seeing any reference of what you might expect from your project and machine. Maybe make a video of the same project in the previous version (2024), so we can see how you would expect this comp to ram preview and we can investigate further.

If you just want to increase performance you can go through the following:
1.) Open the After Effects preferences, go to Media & Disk Cache. Use a fast drive for your Disk cache (SSD). Just to check your performance switch on and off "Enable Preview from Disk Cache". Maybe a slow drive is causing this issue.

2.) In the preferences go to Memory & Performance. Make sure you have enough RAM available for Ae by increasing the reserved RAM to about 10-12 GB. Make sure Multi-Frame Rendering is checked.

Optimizing your preview:

1.) Go to Window-->Preview, if not already open. Choose Resolution to be Auto. Now the the playback will respect, what you have set in the preview window (Full, Half, Quarter). In the preview window click the fast preview icon and check "Adaptive Resolution". 
2.) If it is still to slow reduce the preview framerate by skipping frames (recommended for higher frame rates like 50fps)

General notice: After Effects is working different to Premiere and is calculating each frame, while PR is able to kind of stream. Therefore working with .mp4s can cause some performance instability. In your reference video I can see how the timeline is rendering and caching the frames (greenbar). What you see there is on your RAM. Make the work area a little bit smaller and let the playback run through, so the bar is filled completly green), if your playback runs fluid after it is cached, it is working normal. If you see a blue bar, that is the rendered frames stored on your drive. As soon as your playback length (work area length) is overfilling your RAM preview it should get stored to the disk cache instead. 

I hope this first investigations might already solve your problem, otherwise preserve more detailed previews of your lag of performance. 

Cheers,

Tobi