Participant

RAM Preview not working/extremely slow. Seems to target MXF files (MP2V) but have experienced it with other codecs too.

Forum|Forum|1 day ago
September 28, 2026
3 replies
18 views

I’m using an M1 Macbook Pro and have updated to After Effects 26.5.0

Whenever I bring in an MXF file it either won’t play, or takes a few minutes to generate a few seconds of a preview. I’ve experienced this across the three Macs we use at my work. We’ve reverted to 2025 where the issue isn’t happening.

We use a daily ‘master project’ that we duplicate every morning and use for that days work (for work on a daily tv show). If I create a brand new blank project and import an MXF it’ll play it fine, but as soon as I import the original project, it slows again. If I save the project in 26 as a 25 project and open it in 25 there are no issues.

Nishu Kushwaha

Community Manager

Thanks for reaching out and sorry to hear about the issue. A few things that would help narrow it down:

1. What are your system specs on the machine you're testing on?

2. What are the specs of the affected media (codec, resolution, frame rate)?

3. If it only happens when working from your master template, I'd recommend recreating the template from scratch in the latest version and testing again. Sometimes project-level state carries over corrupted references.

If you can, feel free to share the media and project file with me for testing (via DM if you'd prefer not to share publicly).

Thanks,
Nishu

R

RobShultz

Community Expert

Have you tried doing a: Edit/Purge/All Memory and Disk Cache?

S

Sam McKenzieAuthor

Participant

Actually further testing shows that opening a blank project in 2026 doesn’t fix the issue fully - I get around 10 seconds of preview before it freezes and slows.

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