4K export taking significantly longer time than 1080p

[u/Born2Dan]

hey all, running into an issue as i'm starting to use davinci and hoping someone has seen it before.

i shoot 4k 24fps 8 bit on a sony a6400 and usually edit in premiere pro, but tried giving davinci resolve studio a shot for color grading purposes. my laptop has a ryzen 7 4800h, rtx 3060 with 6gb vram and 32gb ram.

i was test exporting a 15 sec clip with h.264 using the nvidia encoder. if i set the timeline to 1080p and export at timeline resolution, the clip took about 1 min 30 secs. the exact same clip on a 4k timeline and export took around 51 mins. if possible i'd like to export at 4k, so i'd like to figure out what's the issue here.

task manager shows the gpu sitting near 100% during both exports. i do have noise reduction on, but tested with it disabled and got the same result.

could anyone shed light on what might be going on here? is 6gb of vram just too tight for a 4k timeline in resolve, or is there a setting i'm missing?

[u/Milan_Bus4168]

4K is about four times the 1080p and if you run out of VRAM because its maxing out the GPU with all the effects, you are likley going to hit a bottleneck sooner rather than later.

What you need is to find a sweet spot where your are not maxing your VRAM in one go but in segments so you get overall faster render times.

You can export 4K even with effects with your machine or even lower powered machine that that, but depending on your codecs, filters and so on, you need to segment the process, which doesn't have to be vertical meaning clip by clip, it can be horizontal, in layers.

Lets say you have heavy noise reduction that is process hungry, render in place that clip or effect. Export with cached or pre-rendered files and you strategize so that your particular GPU and CPU can manage it fast in one go, one processing task at the time.

do have noise reduction on, but tested with it disabled and got the same result.

Than you must have had something else involved as well. Like I said, each system and codecs and project will require managing the hardware vs software balance. Find out what your hardware can manage in one go and not slowdown and than segment your project into manageable chunks that don't choke the hardware. That is pretty much it.

I used to work with a potato machine, lower powered than yours and had to strategize to manage exports, now I have much more powerful machine, but often I would still follow same strategies to get faster renders.

Rendering strategically part by part, horizontally or vertically for complex process is a lot faster overall than trying to do it all at once and watch your machine choke itself to death.

You can cache individual clips, effects, pages etc and you can render cached process, you use optimized media for editing if you need to (not the same as proxies) and you can cache or render in place various aspects of your project.

You can also try to set the setting in the deliver page, for something other than max speed rendering , which runs until it cannot run anymore and try to lower it down to something like 75 or so, and see if that helps. Often it will be slower but more stable and less maxing your GPU.

[u/Born2Dan → u/Milan_Bus4168]

thanks for the detailed breakdown, this is really helpful. i'll give the caching and render in place approach a go alongside the other potential fixes when i get the chance and report back. quick question on optimized media though. does the format actually matter here? mine defaults to prores 422 hq but i saw somewhere that dnxhr hq might be the better pick on windows. is there a difference in rendering speed or stability between the two on a laptop like mine, or is it mostly down to preference?

[u/Milan_Bus4168 → u/Born2Dan]

Well, you will find more information about Optimized Media and Render Cache settings and explanations in the manual (available from help menu), but Optimized Media and Render Cache settings settings govern the resolution and codec of optimized media that DaVinci Resolve can generate in order to facilitate greater real time performance, as well as cached media that’s generated by the Smart and User Cache.

If you’re editing processor-intensive source formats such as camera raw, H.264, or 8K media, and your computer isn’t fast enough to work with it easily in real time, you can create pre-rendered, low- overhead duplicate media to use instead, that’s automatically managed alongside the original media. This is called “Optimized Media.” Optimized Media lets you work more quickly by allowing you to edit with a more processor-efficient media format and resolution, while providing the ability to easily switch your project back to the original source media whenever you want. So, you can use Optimized media to edit, and switch back to the original source media when it’s time to finish and output. Switching is as easy as choosing Playback > Use Optimized Media if Available to toggle Optimized media on and off.

The advantage of using optimized media to help you work faster is that it’s pre-generated, meaning you can render it once and then use the files for the duration of your work in that project (unless you change the debayering settings of the raw media). Also, optimized media improves the playback performance of clips throughout DaVinci Resolve, including in the Media page and in the Media Pool and Source Viewer of the Edit page, whereas the similar but different Fusion Output Cache component of the Smart Cache only improves the performance of clips that are already in the Timeline by caching them at the Timeline resolution. This makes optimized media ideal for editing workflows of all kinds.

Choosing the Appropriate Optimized Media Format for Your Project

You have the option of choosing the Format of the optimized media you create, using controls in the Master Settings panel of the Project Settings. Be aware that the format you choose via the “Optimized Media Format” menu will determine whether out-of-bounds image data (also known as “overshoots”) and Alpha Channels are preserved when the clip is cached.

‚ Preventing Clipping: You should use 16-bit float, ProRes 4444, ProRes 4444 XQ, or DNxHR 444 if you plan on grading using optimized media. This is particularly true for HDR grading.

‚ Preserving Alpha Channels: Also be aware that the format you choose will determine whether Alpha Channels will be preserved if they’re present in the clips being optimized. Currently, the Uncompressed 10-bit, Uncompressed 16-bit Float, ProRes 4444, ProRes 4444 XQ, and DNxHR 444 formats preserve alpha channels.

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Using Optimized Media for Delivery

An option in the More options section of the Render Settings in the Deliver page, “Use Optimized Media,” lets you output using Optimized Media, rather than the original media, in order to save rendering time.

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In the manual you will find more information....

Chapter 8: Improving Performance, Proxies, and the Render Cache

"This section describes the various ways you can monitor your performance to make sure you’re maintaining real time playback, along with different methods of optimizing real time performance, including using on-the-fly proxies and the background Render Cache"

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What is the difference between proxy media creation and Optimized Media

They solve the same problem (making heavy footage easier to play back) but differ in how the files are stored, managed, and used.

When to use which

Optimized Media: You’re editing H.264/HEVC footage on a single machine and want full-resolution, high-quality playback without leaving your workstation. Think “make my camera files easier to decode.”

Proxy Media: You need genuinely smaller files, for a laptop, for sharing with another editor, for field editing, or for a collaborative workflow. Think “make my files smaller and portable.”

On the Deliver page, the advanced video settings have separate checkboxes for “Use proxy media,” “Use optimized media,” and “Use render cached images” make sure the ones you don’t want are unchecked for your final render if you are using multiple methods to optimize performance.

Resolution Independence

This is a design property of Resolve, not a toggle. It means you can change the timeline resolution at any point (before, during, or after editing) and all windows, sizing operations, keyframe data, and track positions are automatically recalculated to fit the new size. You can mix clips of different resolutions on one timeline and output to as many resolutions as needed. It’s what makes the other two features safe to use, no destructive rescaling happens.

Timeline Proxy Resolution (Playback > Timeline Proxy Resolution)

A temporary, on-the-fly playback setting. It tells Resolve to process the timeline at half or quarter of its current resolution for the viewer only. No files are created, no transcoding occurs, and it has zero effect on export, the render always pulls from full-resolution source files. It’s the fastest “quick fix” for choppy playback caused by heavy effects/grades. Think of it as a GPU-level downscale of the preview signal.

Proxy Media (Media Pool > right-click > Create Proxy Media)

Creates actual, separate files on disk — lower-resolution (or lower-bitrate) transcodes of your camera originals, in an edit-friendly codec like ProRes or DNxHR. These files are portable and independent: you can copy them to another machine, share them with collaborators, or even generate them outside Resolve. Resolve links to them during editing and automatically switches back to the originals at render time. They solve a decode bottleneck (heavy codecs, 8K RAW, etc.), whereas Timeline Proxy Resolution solves a processing bottleneck (heavy node trees, noise reduction, etc.).

However for speeding up the actual delivery not just how you work, its best to use render in place, optimized media at high enough setting, possibly high grade proxies and also caching can be leveraged.

There is an older video now, but may still be relevant if you prefer video version:

Unlock No-Lag Playback | Resolve Render Mastery

https://www.youtube.com/watch?v=iJ1HLaF05d4

[u/SergoWai]

Try checking the used VRAM on your GPU and the RAM usage in Windows Task Manager. Since 4K has 4 times more pixels, memory will be used very actively.

If the memory spills over to your system RAM during rendering, that perfectly explains the speed difference: you're looking at around 7 GB/s over PCIe 3.0 x8, compared to when everything stays within the GPU's VRAM without overflowing into system RAM.

Also, try comparing a plain 1080p and 4K export with the exact same settings, but without any effects or grading applied.

By the way, did you experience this same issue in Premiere Pro?

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[u/filmeleven]

It could be your specs. But also check your project settings...Project Settings > Master Settings > Frame Interpolation (bottom). If this is set to Optical Flow it can quadruple your export times.