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.