UI latency and slow connection handling on CachyOS / KDE Plasma 6 (Avalonia UI)

UI latency and slow connection handling on CachyOS / KDE Plasma 6 (Avalonia UI)

avatar
schmidt2

Hi Devolutions Team,

I am experiencing severe performance issues with RDM on CachyOS (Arch-based, KDE Plasma 6 / Wayland & X11). The issue persists on both native (AUR) and Flatpak versions, as well as with a purely local XML/SQLite data source (Connections.db).

Symptoms:

  • Extreme UI lag: Simple actions like closing a tab, clicking nodes, or opening settings take 5–6 seconds to respond.

  • Double-clicking an entry has a long delay before connection starts.

  • Modifying UI settings, scaling, or disabling H.264 codecs did not resolve the UI thread bottleneck.

System Info:

  • OS: CachyOS (Linux kernel with BORE/EEVDF scheduler)

  • Desktop Environment: KDE Plasma 6 (Wayland / XWayland)

  • RDM Version: [Deine RDM Version eintragen]

Console Log Output:

Below is the output when running RDM via terminal. Noticeably, FreeRDP reports experimental build options with WITH_VERBOSE_WINPR_ASSERT=ON and fails on the H.264 codec context:

flatpak run com.devolutions.remotedesktopmanager
Gtk-Message: 11:40:10.835: Failed to load module "xapp-gtk3-module"
Gtk-Message: 11:40:10.835: Failed to load module "canberra-gtk-module"
[11:40:44:370] [2:00000402] [INFO][Devolutions.Rdp.Credentials] - [Parse]: parsing "s*****", "a****.c*" (Mstsc) => "Username: "s*****" Domain: "a****.c*""
[11:40:44:374] [2:00000402] [INFO][com.freerdp.codec] - [openh264_init]: Using OpenH264 library path from environment: /usr/lib/libopenh264.so
[11:40:44:374] [2:00000402] [WARN][com.freerdp.core.codecs] - [freerdp_client_codecs_prepare]: Failed to create h264 codec context
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: This build is using [experimental] build options:
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: * 'WITH_MBEDTLS=ON'
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: [experimental] build options might crash the application
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: This build is using [runtime-check] build options:
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: * 'WITH_VERBOSE_WINPR_ASSERT=ON'
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: [runtime-check] build options might slow down the application
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn_cipher][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn_cipher][0x7f6f8000a150]: [SSL] {Cipher} build or configuration missing:
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn_cipher][0x7f6f8000a150]: * des-ede3-cbc: RDP security will not work
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.rdp] - [log_build_warn_cipher][0x7f6f8000a150]: *************************************************
[11:40:44:377] [2:00000402] [WARN][com.freerdp.core.nego] - [nego_enable_aad]: This build does not support AAD security, disabling.
[11:40:44:713] [2:00000402] [INFO][com.freerdp.core.auth] - [auth_resolve_sspi_table]: Using SSPI Module: /app/lib/devolutions/RemoteDesktopManager/libDevolutionsSspi.so
[11:40:45:951] [2:00000402] [INFO][com.freerdp.gdi] - [gdi_init_ex]: Local framebuffer format  PIXEL_FORMAT_BGRX32
[11:40:45:951] [2:00000402] [INFO][com.freerdp.gdi] - [gdi_init_ex]: Remote framebuffer format PIXEL_FORMAT_BGRA32
[11:40:45:953] [2:00000402] [INFO][com.freerdp.channels.rdpsnd.client] - [rdpsnd_load_device_plugin]: [static] Loaded alsa backend for rdpsnd
[11:40:45:963] [2:00000402] [INFO][com.freerdp.channels.drdynvc.client] - [dvcman_load_addin]: Loading Dynamic Virtual Channel nowproto
[11:40:45:963] [2:00000402] [INFO][com.freerdp.channels.drdynvc.client] - [dvcman_load_addin]: Loading Dynamic Virtual Channel ainput
[11:40:45:963] [2:00000402] [INFO][com.freerdp.channels.drdynvc.client] - [dvcman_load_addin]: Loading Dynamic Virtual Channel rdpsnd
[11:40:45:963] [2:00000402] [INFO][com.freerdp.channels.drdynvc.client] - [dvcman_load_addin]: Loading Dynamic Virtual Channel rdpgfx
[11:40:45:963] [2:00000402] [INFO][com.freerdp.channels.drdynvc.client] - [dvcman_load_addin]: Loading Dynamic Virtual Channel disp
[11:40:45:964] [2:00000402] [WARN][com.winpr.thread] - [SetThreadPriority]: pthread_setschedprio(0) not implemented, requires POSIX 2008 or later
[11:40:46:004] [2:0000041c] [WARN][com.freerdp.core.codecs] - [freerdp_client_codecs_prepare]: Failed to create h264 codec context
[11:40:46:213] [2:0000041d] [INFO][com.freerdp.client.common] - [client_common_save_session_info]: Logon Info V2 [AKROS\schmda [2]]
[11:40:46:213] [2:0000041d] [INFO][com.freerdp.client.common] - [client_common_save_session_info]: Logon Extended Info [cookie: TRUE, LogonId: 2, errorInfo: FALSE, notifyType: 0, notifyData: 0]
[11:40:46:309] [2:0000041c] [INFO][com.freerdp.channels.rdpsnd.client] - [rdpsnd_load_device_plugin]: [dynamic] Loaded alsa backend for rdpsnd

Thanks

David

All Comments (5)

avatar
Carl Marien

Hello David,

Thank you for the detailed report and for including the console output.

The log shows that the RDP connection itself sets up in under two seconds, which is normal.

The H.264 message only means that the OpenH264 library path from your environment cannot be loaded inside the Flatpak sandbox, so RDM falls back to another codec.

The “experimental” and “runtime-check” build warnings are standard FreeRDP messages, and they do not explain the delays you see in the interface.

To find the source of the 5 to 6 second lag, could you send us the following?

  • The exact RDM version, from Help > About.

  • Whether an earlier RDM version was fast on this same machine.

Could you also try these two quick tests and tell us whether the lag changes?

  • Start RDM with the accessibility bridge turned off:

flatpak run --env=NO_AT_BRIDGE=1 com.devolutions.remotedesktopmanager

  • Create a new local data source with a single entry, then test again with no session open.

Please note that the AUR package is maintained by the community, so the Flatpak build is the best one to use for these tests.

Best regards,

Carl Marien

avatar
schmidt2

Hi Carl,

thanks for the reply!

Remote Desktop Manager 2026.3.1.2 64-bit
Runtime: .NET 10.0.13
Platform: GNOME 49 (Flatpak runtime)
Workspace: Local data source
Allocated memory: 138 MB

flatpak run --env=NO_AT_BRIDGE=1 com.devolutions.remotedesktopmanager

makes it better already, does this make sense?

Also clicking on "Help" -> "About" took quite a delay to open...so I think it is "just" a UI thing?

avatar
Carl Marien

Hello David,

Thank you for the detailed report.

The console messages you shared come from the RDP engine and are expected with our build. They are not the cause of the slow interface.

We are already tracking a similar slowdown reported on KDE Plasma, and your information will help our developers reproduce it.

Could you please send us the following:

1. Your exact RDM version (Help > About).

2. The System diagnostic: in RDM, go to Help > Diagnostic, then copy or save the report and attach it here.

3. Whether the delay happens in both the Wayland and the X11 (Plasma X11) session, or only one of them.

4. If possible, whether the delay also happens with RDM 2026.3.0.5 or 2026.2.2.2. This tells us whether it started with a recent update.

5. Whether the delay happens with a brand-new, empty local data source and no sessions open.

If you can, a short screen recording of the delay would also help.

https://send.devolutions.com/envelope/7232d142-bf9a-4edd-974a-c374e03456a2

Best regards,

Carl Marien

avatar
schmidt2

Hi Carl,

I'll try to report here:

  1. 2026.3.1.2 64-bit

  2. system-diagnostis attached - interesting, it does not see Internet connected?

  3. My CachyOS was running with XFCE (and X11) before and I had the same issue.

  4. 2026.2.2.2 is not really different.

  5. To test this, is it enough to add a new empty workspace and open this one? Or move away all config files from conf dir?

Maybe the "internet not connected" already gives a hint?

Edit: Connected via VPN, but internet traffic is not tunneled, only traffic to company networks.

Best regards

David

avatar
Carl Marien

Hello,

Thank you for the System diagnostic.

I’ve sent it, along with your description of the issue, to our QA and development teams. They are already looking into a similar slowdown on KDE Plasma, and your details will help them try to reproduce it.

I’ll keep you updated as soon as I hear back from the team.

Best regards,

Carl Marien

1