Since Resolve 20 playback occasionally lags, why?

Hi

I noticed this in the beta version, but its remained the same with all the updates. I don't remember having this issue before v20. This didn't happen before, and it happens even if I put proxy mode quality on the lowest, with no grade at all. I am running footage off Crucial X9 pro SSD's, which are running at 900mbps when tested

I am just playing a single video and audio track, 4k 25p, mp4. It plays back fine for 20 or 30 seconds, and then it lags a bit and stutters, and after that the audio is a bit out of sync, until I stop and start again.

I watch the frames per second above the viewer, and it's green and says 25 to start with, but as this lag happens, it seems to jump up to around 38, and then back down. I have no idea why thats happening

Can anyone help, it's making working incredibly painful!

Thanks

Anyone?

1) 900 mbps isn't very much. I'd be deeply concerned if it was only 900 mbps. 900 MBps though? that'd be more in line with what I was expecting.

2) I suspect logs (see the FAQ) would be helpful

3) mediainfo on the files?

1) 900 mbps isn't very much. I'd be deeply concerned if it was only 900 mbps. 900 MBps though? that'd be more in line with what I was expecting.

2) I suspect logs (see the FAQ) would be helpful

3) mediainfo on the files?

Sorry for the slow reply I was away

yes 900MBps, its similar on all my SSDs

I can't see anything about logs on the FAQ. DO you mean Log files, are these not just when there is a crash?

I will copy the MediaInfo below. I just don't understand why this is happening only in v20 when it was fine before.

MediaInfo :

General
Complete name : /Volumes/TBP Drive 4tb/EP6_Sarah/Host cam/TBP_EP6_Host_TAKE_1.MP4
Format : XAVC
Codec ID : XAVC (XAVC/mp42/iso6)
File size : 61.9 GiB
Duration : 1 h 0 min
Overall bit rate mode : Variable
Overall bit rate : 146 Mb/s
Frame rate : 25.000 FPS
Encoded date : 2025-06-02 09:16:14 UTC
Tagged date : 2025-06-02 09:16:14 UTC

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High 4:2:2@L5.1
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 2 frames
Format settings, GOP : M=3, N=12
Format settings, Slice count : 8 slices per frame
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1 h 0 min
Bit rate mode : Variable
Bit rate : 140 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 10 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.675
Stream size : 59.5 GiB (96%)
Writing library : AVC Coding
Encoded date : 2025-06-02 09:16:14 UTC
Tagged date : 2025-06-02 09:16:14 UTC
Color range : Full
Metas : 3
Codec configuration box : avcC

Audio
ID : 2
Format : PCM
Format settings : Big / Signed
Codec ID : twos
Duration : 1 h 0 min
Bit rate mode : Constant
Bit rate : 1 536 kb/s
Channel(s) : 2 channels
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Stream size : 669 MiB (1%)
Encoded date : 2025-06-02 09:16:14 UTC
Tagged date : 2025-06-02 09:16:14 UTC

Other
ID : 3
Type : meta
Format : Sony Real Time Metadata
Codec ID : rtmd
Duration : 1 h 0 min
Bit rate mode : Constant
Time code of first frame : 11:15:06:06
Encoded date : 2025-06-02 09:16:14 UTC
Tagged date : 2025-06-02 09:16:14 UTC
TransferCharacteristics_FirstFrame : 0E06040101010605
ColorPrimaries_FirstFrame : BT.709
MatrixCoefficients_FirstFrame : BT.709
IrisFNumber_FirstFrame : 1.804607
FocusPositionFromImagePlane_FirstFrame : 2.828 m
LensZoom35mmStillCameraEquivalent_FirstF : 52.600 mm
LensZoomActualFocalLength_FirstFrame : 50.000 mm
FocusRingPosition_FirstFrame : 84.6649%
AutoExposureMode_FirstFrame : Manual
AutoFocusSensingAreaSetting_FirstFrame : Single Spot Sensing Auto
ImageSensorDimensionEffectiveWidth_First : 35.880 mm
ImageSensorDimensionEffectiveHeight_Firs : 20.183 mm
CaptureFrameRate_FirstFrame : 25.000 fps
ShutterSpeed_Angle_FirstFrame : 177.5°
ShutterSpeed_Time_FirstFrame : 1/51 s
CameraMasterGainAdjustment_FirstFrame : 0.00 dB
ISOSensitivity_FirstFrame : 800
ElectricalExtenderMagnification_FirstFra : 100%
AutoWhiteBalanceMode_FirstFrame : Preset
ExposureIndexofPhotoMeter_FirstFrame : 800

Does Resolve 20 work on macOS Ventura? At least this is what your signature says.

Does Resolve 20 work on macOS Ventura? At least this is what your signature says.

I've updated to Sequoia, the issue remains the same on both!

Apart forn the ocassional lags was Resolve 20 runing ok on Ventura?

OP: You need to post your logs per the instructions in 'FAQs for Support and Troubleshooting.' You also need to post your system specs. We don't know if you're working on a super computer or an abacus. You need to tell us this stuff.

What have you done to try to fix the issue? You need to tell us this stuff.

Have you read through the hundreds of other posts asking for the exact same info? What did you find there?

This forum has become 90% "Why Resolve slow?" and 10% "I can't customize the UI?!?!" while anything else is instantly buried on the 2nd page.

For the 20,000th time: Clear your system cache. Clear your Resolve cache. Do a disk speed test and make sure your disks are fast enough. If you use nvme drives, make sure you have at least 1/3 free space. If this doesn't fix the issue, refer to the top of this post.

Your drive may have a smallish cache.

I can't remember but doesn't the BM drive test allow you to use a larger file for the speed test? If so use that or a different program that lets you test large file transfers.

Apart forn the ocassional lags was Resolve 20 runing ok on Ventura?

Hi, yes the only issue was when I updated to 20 that these occasional lags started, where the frame rate would suddenly go up high and then low.

Updating to Sequoia I've noticed no difference at all

OP: You need to post your logs per the instructions in 'FAQs for Support and Troubleshooting.' You also need to post your system specs. We don't know if you're working on a super computer or an abacus. You need to tell us this stuff.

What have you done to try to fix the issue? You need to tell us this stuff.

Have you read through the hundreds of other posts asking for the exact same info? What did you find there?

This forum has become 90% "Why Resolve slow?" and 10% "I can't customize the UI?!?!" while anything else is instantly buried on the 2nd page.

For the 20,000th time: Clear your system cache. Clear your Resolve cache. Do a disk speed test and make sure your disks are fast enough. If you use nvme drives, make sure you have at least 1/3 free space. If this doesn't fix the issue, refer to the top of this post.

Sorry I thought the details were in my signature. The reason I didn't explain much was because everything was working fine, until the V20 update and then this issue started, so I assumed that would narrow it down to it being related to that

Laptop - MacBook Pro M2 MAX, 64gb Ram, 1tb SSD
OS - Sequoia 15.5
Resolve version - 20.0 build 49
External SSD - Crucial X9 pro 2tb
External SSD speeds - Write 830MB/s, Read 918MB/s

I was using this exact SSD on Resolve 19 with similar projects, the same files from the same camera, with no issues.

I have cleared Caches. The cache is set to be on the SSD or it gets too large, but I've always done that with no issues. I've put resolve timeline playback resolution to quarter and it makes no difference (I didn't used to need to do this). I've turned off all grades, all audio effects etc.

Is there anything else that would be helpful to share?

Your system should be very capable to handle mostly everything!

Did you try manually deleting the cacheclip folder instead of deleting cache from Resolve itself? 90% of weirdness can be fixed by doing that. You need to have Resolve not running in order to do so.

And good point about making sure your main SSD is not full.

Failing that, it should just work

Apart forn the ocassional lags was Resolve 20 runing ok on Ventura?

Hi, yes the only issue was when I updated to 20 that these occasional lags started, where the frame rate would suddenly go up high and then low.

Updating to Sequoia I've noticed no difference at all

Hey Thanks Alex!
Did you install Resolve 20 on Ventura in paralel with Resolve 19? If so, those lags were only in R20 or once you installed R20 they appeared in Resolve 19 as well?

Thanks!

Did you try making a new library, and new project in that library, and see if the problems still occur?

I would also try temporarily removing/disable all 3rd party Resolve plugins, especially VSTs.

viewtopic.php?f=21&t=199198

One thing: can you check that your Resolve is actually running in native Apple code and not via Rosetta? It's happened before on these forums, people noticed performance issues and turned out that Resolve somehow installed the intel x86 version.

hi,

I had the same, started after working for some time in V20.
After deleting some of the cache it worked fine again.
As a matter of fact, I'm still deleting when I have time, it takes a lot of time.
While deleting, all the other Resolve sets working on the same cloudstore slow down.
Didn't expect that to happen, that's its so intensive to delete cache

the best option to delete the cache is to close resolve and delete the cache folder.

the best option to delete the cache is to close resolve and delete the cache folder.

why is it better?
I did both, but both interrupted the other Resolve sets, so I better wait for a quiet moment

I do not know but I found that when I had weird issues, deleting the folder fixed the issue.

Did you try making a new library, and new project in that library, and see if the problems still occur?

I would also try temporarily removing/disable all 3rd party Resolve plugins, especially VSTs.

viewtopic.php?f=21&t=199198

Thanks I just tried a new library and it still happens. As for VSTs I've disabled all but a couple I need, but this happens when I have no VSTs loaded at all

And the main thing is still that it wasn't happening before v20

hi,

I had the same, started after working for some time in V20.
After deleting some of the cache it worked fine again.
As a matter of fact, I'm still deleting when I have time, it takes a lot of time.
While deleting, all the other Resolve sets working on the same cloudstore slow down.
Didn't expect that to happen, that's its so intensive to delete cache

thats interesting it happened for you on V20 also. I have deleted the cache though, multiple times

Just an update - I've deleted the cache, I've created a new project library, dropped in the clips fresh. I even just had one video track, which should be no issue whatsoever. It will play for 10 seconds and then you see the playhead lags, and the FPS either jumps up to 38fps and then down, or seems to drop momentarily to 10fps and then up to 38fps and then back to 25

But equally as annoying as the lag, is that after it lags, it plays out of sync, so I have to stop and start to get the audio to be in sync again.

I've been having to work this way on a current project and it's driving me mad! But I can't work out whats going on

Any other ideas would be greatly appreciated!

One thing: can you check that your Resolve is actually running in native Apple code and not via Rosetta? It's happened before on these forums, people noticed performance issues and turned out that Resolve somehow installed the intel x86 version.

yes I have the right one installed, but just to be certain I re downloaded the Mac version and installed it again. No change

Even with timeline playback resolution on quarter and one video track, after about 30 seconds or a minute it will lag!

The issue that was reported was that DR for Mac was installed but somehow it managed to install the intel version.

To check you don't need to re-install. Open Activity monitor and check what it says on Resolve: Intel or Apple?

[Shrinivas Ramani]

The Mac installers are universal binaries. There are no separate Intel and ARM versions. This means the app runs native on both Intel and ARM64.

And lastly, because it has come up before, Rosetta helps Resolve deal with third party libraries and binaries that need Rosetta to operate.

Shrinivas,

Yes, I am aware Rosetta is required for DR on Apple for some libraries - but some time ago someone reported performance issues with their DR and it turned out that somehow the main DR program was running under Rosetta on an Apple Silicon machine. A reinstall fixed that. I think Dwaine was involved in that thread.

I was just suggesting that Alex could check that that isn't his problem.

...Even with timeline playback resolution on quarter and one video track, after about 30 seconds or a minute it will lag!

That is Sony 4k/23.98 10-bit 4:2:2 XAVC-S. The GOP parameters of M=3, N=12 means GOP size of 12 frames and 3 reference frames. That is a standard format, and it should play smoothly at 1x on an M2 Max.

Please verify in DaVinci Resolve>Preferences>System>Decode Options that "Decode H.264/H.265 using hardware acceleration" is enabled.

If that's enabled and playback is still laggy at 1x speed, please create Resolve diagnostic logs by doing Help>Create Diagnostic Logs on Desktop. That will take a minute or so.

Then, place the file on a file-sharing site and provide links to the files here. Make sure the links don't require access credentials.

I had a similar issue, but on Windows. What helped me is disabling Direct I/O on Preferences - System - Media Storage. If it's already disabled, I think you can try enabling it, as it might have some impact.

...Even with timeline playback resolution on quarter and one video track, after about 30 seconds or a minute it will lag!

That is Sony 4k/23.98 10-bit 4:2:2 XAVC-S. The GOP parameters of M=3, N=12 means GOP size of 12 frames and 3 reference frames. That is a standard format, and it should play smoothly at 1x on an M2 Max.

Please verify in DaVinci Resolve>Preferences>System>Decode Options that "Decode H.264/H.265 using hardware acceleration" is enabled.

If that's enabled and playback is still laggy at 1x speed, please create Resolve diagnostic logs by doing Help>Create Diagnostic Logs on Desktop. That will take a minute or so.

Then, place the file on a file-sharing site and provide links to the files here. Make sure the links don't require access credentials.

thanks for helping, this is driving me nuts

I do have "Decode H.264/H.265 using hardware acceleration" enabled. I also turned it off and on, and restarted, and still get this occasional lag - FPS jumps to 38, then down to 12 and then plays out of sync

Here is the log : https://drive.google.com/file/d/1L5EcE4 ... share_link

thank you!

Your logs might imply you have over 1,100 third-party Fusion macros. Is that possible? Do you see anything familiar listed here: ~/Movies/Motion Templates/

Or here: /Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/

Or here: ~/Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/Templates/

It's possible IF you had lots of third-party Fusion macros that Resolve 20 may have less efficient scanning of these, and this in turn could theoretically cause performance overhead slowing down your playback. This is just a guess.

I'm having this same issue on a brand new M3 Ultra Mac Studio running MacOS Sequoia 15.3.

This seems to happen when the playhead is coming up on a rendered/cached clip. It stutters just before the clip, then plays back a few frames out of sync. I have to stop playback and restart for it to play in sync again.

Oddly, I've noticed that once Resolve has been open for a while, this seems to get better. No idea if that's related to something or just a coincidence.

The timeline is not complex. I'm editing with 1080p24 ProRes Proxy. The cache location is set to a thunderbolt 4 OWC NVMe drive. The cache file format is ProRes Proxy. The media is hosted on an SNS NAS connected via 10Gb Ethernet.

I've tried changing the playback resolution and disabling all color and fusion effects. At first, I thought it improved the issue. But it eventually happened even with that turned on.

Any insight from BMD on this issue would be greatly appreciated. It seems like this is not an isolated issue based on all the comments.

You can view my system report and logs here: https://drive.google.com/drive/folders/10m7O5vFQ90ltaBeQa-dCeo4mPwrDMJwU?usp=sharing

Your logs might imply you have over 1,100 third-party Fusion macros. Is that possible? Do you see anything familiar listed here: ~/Movies/Motion Templates/

Or here: /Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/

Or here: ~/Library/Application Support/Blackmagic Design/DaVinci Resolve/Fusion/Templates/

It's possible IF you had lots of third-party Fusion macros that Resolve 20 may have less efficient scanning of these, and this in turn could theoretically cause performance overhead slowing down your playback. This is just a guess.

Thanks I found some templates, but nothing like 1100! I did get lots of third party titles and macros before, but it seems only the Titles show in Resolve now, not the macros, I wonder if they aren't compatible with v20?

Should I just move them out of those folders?

Please run this terminal command and send me the results via the below Dropbox location. Copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

find ~/Movies -type f \( -name '*.setting' -o -name '*.macro' \) > ~/Documents/FusionTemplates.txt

- Quit Resolve.

- Delete the preview cache. Copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

rm -rf ~/Library/Application\ Support/Blackmagic\ Design/DaVinci\ Resolve/Fusion/.previewCache

- Relaunch Resolve and wait two minutes so it finishes its first scan.

- Examine performance

- If still slow, do the below command in terminal and send me the output file via this Dropbox location. As before, copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

https://www.dropbox.com/scl/fo/gjnr6smt ... jyka1&dl=0

find ~/Movies/Motion\ Templates.localized -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g' > ~/Documents/MotionTemplatesList.txt

I didn't have any fusion templates that showed up in that file, and I might be speaking too soon. But this seems to have helped.

I re-cached my timeline and playback is smoother now.

I'll keep you posted if anything changes.

Please run this terminal command and send me the results via the below Dropbox location. Copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

find ~/Movies -type f \( -name '*.setting' -o -name '*.macro' \) > ~/Documents/FusionTemplates.txt

- Quit Resolve.

- Delete the preview cache. Copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

rm -rf ~/Library/Application\ Support/Blackmagic\ Design/DaVinci\ Resolve/Fusion/.previewCache

- Relaunch Resolve and wait two minutes so it finishes its first scan.

- Examine performance

- If still slow, do the below command in terminal and send me the output file via this Dropbox location. As before, copy and paste to terminal, all on one line. Drag the terminal width wider if needed.

https://www.dropbox.com/scl/fo/gjnr6smt ... jyka1&dl=0

find ~/Movies/Motion\ Templates.localized -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g' > ~/Documents/MotionTemplatesList.txt

Wow thanks for all this help!

I actually tried moving all the titles and templates out of the Library folder you originally mentioned, and it seems to be running better. I've left it going for a few mins and it seems ok. I will need to test it for longer when editing a project which I should be doing soon

I did afterwards also enter the terminal commands you have given above. Nothing happened when I put any of them in, is that correct? I don't think it is as I put the last one you mentioned : 'find ~/Movies/Motion\ Templates.localized -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g' > ~/Documents/MotionTemplatesList.txt'

And nothing happened, it didn't open a folder or create anything to send you.

I'd just like to understand

I didn't have any fusion templates that showed up in that file, and I might be speaking too soon. But this seems to have helped.

I re-cached my timeline and playback is smoother now.

I'll keep you posted if anything changes.

So what happened when you put those in to terminal? As I didn't get a file come up

Also what do you mean re cached your timeline? I have deleted my cache, is that the same

So what happened when you put those in to terminal? As I didn't get a file come up

Also what do you mean re cached your timeline? I have deleted my cache, is that the same

A file was created but there was nothing in it. I think that's because I didn't have any templates in the location the terminal command was referencing.

By "re-caching," I mean I deleted my cache (actually reformatted the cache drive) then re-rendered the timeline in Smart caching mode.

So what happened when you put those in to terminal? As I didn't get a file come up

Also what do you mean re cached your timeline? I have deleted my cache, is that the same

A file was created but there was nothing in it. I think that's because I didn't have any templates in the location the terminal command was referencing.

By "re-caching," I mean I deleted my cache (actually reformatted the cache drive) then re-rendered the timeline in Smart caching mode.

OK thanks!