Premiere lagging - not responding

[magpiemel]

Once my sequence is over a few minutes (admittedly with several video layers & effects) Premiere is lagging - sometimes not responding when moving playhead to a different part of the sequence. Or not responding to the playbar.

Offline media is H.264.mp4 in a variety of frame sizes. 5000+ clips. The show is comprised entirely of stock footage). 

I'm applying ’Scale to frame size’ - so clips fit the timeline. All media results in a yellow warning render bar.

Working in a Premiere Production - with separate projects for the different string outs, 'bins' of media and different project files for my cuts.

Working from with long string outs of media. Editing into my edit sequences (which are in separate projects).

I'm worried I'm having performance issues - working on short sequences. Eventually I'll be working with a 50 min sequence.

Sequence settings 1920x1080. 

I was advised to change my Preview codec to Apple ProRes Proxy. (Should I try Apple ProRes LT instead?)

Specs:

Premiere 2025

Mac mini Apple M4 Pro 24GB

macOS: Sequoia 15.5

Media, Projects, media cache etc is on a supplied external HDD.

Also using Logitech G502 mouse (with G Hub software).

Is the H.264 offline media the culprit? Should I make Pores proxies of my media? I'm heisitant to transcode 1000s of files if it isn't going to help.

Are there any other settings I can try changing?

Thanks so much for reading!

[magpiemel]

These are my current (default) audio hardware settings.

Should I try changing the Audio Hardware Default Input setting to No Input?

It comes up with a warning message when I go to change it.

[Peru Bob]

Should I try changing the Audio Hardware Default Input setting to No Input?

By @magpiemel

Yes.

[Peru Bob]

Media, Projects, media cache etc is on a supplied external HDD.

By @magpiemel

What type of external drive?

[R Neil Haugen]

Ok, long-GOP media is nasty stuff, and even if a system is good enough at it to handle one or two tracks, basic playback, you start adding effects and scaling ... and you're throwing a ton of per frame computational work at the computer.

Which is why going to ProRes/DNx/Cineform proxies may help immensely. May, again, you'll need to test of course.

And sustained data reading over time is a lot different than the optimal speed that an external drive connection can show. I've seen things where once the cache was filled ... performance dropped by 30% to 50%. So that means data in/out for all that computational work is not coming in after the first minute or so of playback at the speed it started at.

The drive will show a lowered speed, and people go ... well, it's not using the full speed of the drive connection! I get 150Mbps connection, it's only using 80!

Well ... that again might be that after the cache is loaded, that is all it can sustain in a constant running.

And as to the long-GOP ... I've had a lot of people who were stunned that their computer, which balked at 2 tracks of UHD H.264, could get good playback with 3-4 streams of 6K or 8K RED media ... but that was on internal drives of course.

[magpiemel]

Thanks Peru Bob,

I've tried setting the audio input to 'No Input'. Will see how that goes.

The supplied external drive is ExFAT. I've attached a speed test.

Thanks R Neil Haugen; definitely agree I would never choose to work with H.264 media. I will try to run a test.

[jamieclarke]

Hi @magpiemel -  What exact version of Premiere Pro are you using?  What effects are you using?

Let us know how things go after trying the suggestions.

Neil and Peru Bob than you for helping.

[magpiemel]

Hi Jamie

Version: 2025.3 (Build 84)

Effects: scale to frame size, time remapping, split screens (2, 3 & 4-way) and transitons

Cheers