Severe playback stutter and UI lag with long H.264/H.265 clips

[Gabby16bit]

• macOS (M2 Ultra). Same behavior observed on other systems as well.

• Adobe Premiere Pro (latest).

• Media: single 3840×1080 clip split into two 1920×1080 sources; also happens with two native 1920×1080 tracks.

• Codecs tested: H.265 (HEVC) and H.264 (AVC).

• Issue

Premiere becomes progressively sluggish and starts stuttering badly when working with long clips (around 40 minutes). After a restart, playback is smooth for a few minutes, then the stutter and UI lag return. This makes editing unreliable and breaks focus.

Steps to Reproduce:

Create a sequence at 1920×1080.

1. Import a ~40-minute clip (tested with 3840×1080 HEVC/H.264).

2. Split the 3840×1080 clip into two 1920×1080 halves (or use two separate 1920×1080 tracks).

3. Play, scrub, and make basic edits for several minutes.

Expected

Consistent, smooth playback and responsive UI throughout the session.

Actual

• Playback begins to stutter heavily after a few minutes.

• The entire application feels sluggish (laggy UI, delayed responses).

• Restarting Premiere temporarily restores smooth playback, but the issue returns.

Notes

• Occurs with both H.265 and H.264 sources.

• Not specific to a single machine; I’ve seen this on multiple systems over the years.

Request

Please investigate long-clip handling/performance in Premiere. This has impacted my workflow for years and makes longer edits impractical.

I have attached a video of the problem:

[Ann Bens]

Premiere latest: which version and build would that be?

[Gabby16bit]

25.4.0 Build 99

[Dani_V.]

Hi @Gabby16bit,

Thank you for reporting a problem and for providing all this information. I'm sorry you've been experiencing this issue.

What frame rate are your clips? Is it possible these are clips with variable frame rate? You can check if you right-click your clip in the Project panel > Media File Properties, it would say 'Variable Frame Rate Detected' under the clip information. If they are, VFR footage is not really editing friendly and converting these to a constant frame rate would likely help a lot with performance, along with making proxies (like ProRes) for the footage for smoother editing.

For settings if you go to Preferences > Audio Hardware, try setting the Default Input to 'No Input'. And if you right-click on the Program monitor, deselect 'High Quality Playback' if selected. This might be able to help with some of the stuttering you are seeing as well.

Sorry for the frustration and hope we can help you soon,
Dani

[Gabby16bit]

Hi Dani, thanks for the answer, i confirm that everything is CBR and no i didn't had activate High quality playback, the only thing i had activated is the "Default input" to my apollo twin Solo. I will try to edit without that if there is any difference i will let you know.

[Gabby16bit]

I have tried to disable Input and it was better than last time, but still sometimes if Freeze or stutter, i also edit the video at 2x or 3x speed to be faster and that could stutter sometime the video, hope the performance will improve. Just try to focus more on GPU use than CPU, i think we should go more on the GPU side for NLE's