I am working with an astro timelapse that involves a sequence of high-resolution image files on external storage. Clearly, the USB connection is FAR too slow to allow playback or scrubbing. However, my RAM is more than large enough to fit the entire sequence. If only Premiere would actually use it in a vaguely sensible manner.
When I hit play, the USB 3 connection immediately maxes out, and Premiere manages to display perhaps two or three frames out of the 14-second clip. One would expect that Premiere would try loading the source sequence into memory, but nope! RAM utilization hardly budges from its 8GB or so "resting" value. However, when I try to scrub back and forth, I can see Premiere loading from the USB drive to RAM. The drive connection remains pegged, and the RAM utilization steadily increases up to a final value of around 30GB. Note that I have to keep scrubbing around to sections it hasn't "gotten" yet, or it will stop loading more. Once this several-minute process is done, great! Now the sequence is in memory, and I can scrub freely. One would hope that now I could play the clip, since all the source material is already loaded in? No! The moment I hit play, the RAM utilization drops back down to 8GB! It dumps everything it had loaded, and goes back to the futile effort of play straight off of the USB drive! This is absurdly poor optimization. Note that neither my CPU nor GPU budge above idle at any point, so it's obvious they are not the bottleneck, and I still have RAM to spare left over. It doesn't even try to cache anything to the video preview folder on my SSD.
Is there some fix for this ridiculous behavior, or is Premiere simply incapable of managing this type of workload?
I'm unaware of any fix, but as a general advice - try to resize highres MultiMegapix images to the timeline resolution before editing, that should make it all much faster.
I understand that certainly would help, but I think it would also cause other issues. There's a fair amount of image editing that needs to be keyframed to account for light changes over the course of the night, as well as loads of noise reduction stuff. Due to all this editing that's happening in Premiere (or a linked After Effects clip for temporal noise reduction) to images that have already been exported from Lightroom, I am worried that downsampling before importing to Premiere will significantly reduce my output quality, especially as the noise reduction algorithms will have less information to work with. Do you have any advice?
Downsampling has denoise effect of itself. Unless you do additional framing/zooming in of these images in Premiere, I don't see how it can be a problem. . Why not to create a copy of the project, and try how it works for downsized images? Btw, here is a good temporal denoiser, worth to try, althou it's standalone, not a plugin: https://1drv.ms/f/s!Andr88T403SpapbOPF2tnEGLnQ0
You've got several things that all involve a lot of hardware demands going on at the same time. Yea, you're gonna get issues here. What you're trying to do all in one step would tax my rig ... 24 cores, 128Gb of RAM and a 2080Ti, with eight internal large SSD drives.
FIrst ... the other person's comment about getting the image sizes down is spot-on. Though you may need to do it in a different way to make this project work properly.
First ... do any resizing work you need on the images going down the timeline. Then apply video denoising (Neat I hope) and do a render & replace operation to a good 'DI' intermediate intraframe codec like ProRes, Cineform, or DNxHD/R.
Now take that set of replaced clips and do the next step of your process. This is how much of complex editing & effects have to work.
Sorry for the performance issues related to a still image slide show. I would place all the images on the fastest drive you have. USB C is sufficient. It sounds like you are expecting the images are loaded into RAM. That occurs in After Effects but not Premiere Pro. Image playback is more CPU/GPU based while RAM is used for other tasks, like containing and holding all the timeline information.
As others have suggested, high res images are overkill. You need the right size not something too large in frame size. I usually just double the frame size of the sequence and that is fine for all kinds of scaling and repositioning of the images (via keyframes, of course).
Before I begin animating a slide show, I always "clean" the images in Photoshop to make them standardized. Once you have standarized the sizing before the images even come into Premiere, you can get a nice workflow going which would include motion presets. These presets would speed up your workflow markedly. Consider using those.
Come back with any questions.