Massive delays, hangs on scene switching

jbai256

New Member
Hi all,

New member here. I've got a few Ubuntu 20.04 desktops that have the same hardware and OS configuration. All of them ran great until Ubuntu 20.04 reached end-of-life. At that point I wiped the disk and installed 22.04 from scratch. I then installed OBS from the official obs-studio PPA (version 27.2.3). Oddly, however, I immediately started to see heavy delays and even app hangs when I tried switching scenes. Delays can be anywhere from 20 seconds to several minutes.

The scenes pull video from two IP cameras (Axis/RSTP) per scene and then publish the a composite stream (one video full screen, one video subsetted (pip)) to a broadcasting server.

Hardware:

Code:
# lspci
00:00.0 Host bridge: Intel Corporation Device a703 (rev 01)
00:01.0 PCI bridge: Intel Corporation Device a70d (rev 01)
00:04.0 Signal processing controller: Intel Corporation Device a71d (rev 01)
00:08.0 System peripheral: Intel Corporation Device a74f (rev 01)
00:0a.0 Signal processing controller: Intel Corporation Device a77d (rev 01)
00:14.0 USB controller: Intel Corporation Device 7ae0 (rev 11)
00:14.2 RAM memory: Intel Corporation Device 7aa7 (rev 11)
00:15.0 Serial bus controller: Intel Corporation Device 7acc (rev 11)
00:16.0 Communication controller: Intel Corporation Device 7ae8 (rev 11)
00:17.0 SATA controller: Intel Corporation Device 7ae2 (rev 11)
00:1c.0 PCI bridge: Intel Corporation Device 7abe (rev 11)
00:1c.7 PCI bridge: Intel Corporation Device 7abf (rev 11)
00:1d.0 PCI bridge: Intel Corporation Device 7ab4 (rev 11)
00:1f.0 ISA bridge: Intel Corporation Device 7a85 (rev 11)
00:1f.3 Audio device: Intel Corporation Device 7ad0 (rev 11)
00:1f.4 SMBus: Intel Corporation Device 7aa3 (rev 11)
00:1f.5 Serial bus controller: Intel Corporation Device 7aa4 (rev 11)
01:00.0 VGA compatible controller: NVIDIA Corporation Device 2882 (rev a1)
01:00.1 Audio device: NVIDIA Corporation Device 22be (rev a1)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 16)
03:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device b852
04:00.0 Non-Volatile memory controller: Sandisk Corp Device 5017 (rev 01)

Nvidia driver info....
Code:
# nvidia-smi
Thu Oct 30 15:33:01 2025      
+-----------------------------------------------------------------------------------------+
| NVIDIA-SMI 580.95.05              Driver Version: 580.95.05      CUDA Version: 13.0     |
+-----------------------------------------+------------------------+----------------------+
| GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
| Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
|                                         |                        |               MIG M. |
|=========================================+========================+======================|
|   0  NVIDIA GeForce RTX 4060        Off |   00000000:01:00.0  On |                  N/A |
| 37%   33C    P8            N/A  /  115W |     195MiB /   8188MiB |     16%      Default |
|                                         |                        |                  N/A |
+-----------------------------------------+------------------------+----------------------+

+-----------------------------------------------------------------------------------------+
| Processes:                                                                              |
|  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
|        ID   ID                                                               Usage      |
|=========================================================================================|
|    0   N/A  N/A            1388      G   /usr/lib/xorg/Xorg                       80MiB |
|    0   N/A  N/A            1741      G   /usr/bin/gnome-shell                     18MiB |
|    0   N/A  N/A          482943      G   obs                                      28MiB |
+-----------------------------------------------------------------------------------------+

CPU and memory utilization doesn't seem to be any different than it was with Ubuntu 20.04. These boxes are using virtualGL and x11vnc (they run headless via a HDMI dongle; I remote into them with Apache Guacamole). The cameras are on solid network links of at least 100Mbps (most are 1Gbps links).

The OBS logs in ~/.config/obs-studio/logs don't seem to be capturing anything at all. I switched scenes before streaming anything while testing this morning, and there is no log at all for today.

One last item. The ~/.config/obs-studio folder was copied directly from one of the machines before I wiped 22.04 off it it. Could there be a structural difference that is causing the delays?

Any suggestions as to what might be causing the slow down when switching scenes? If I can get to the right scene, it broadcasts fine. Help is appreciated. Thank you!
 
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