[mythtv-users] mythfrontend performance over x11vnc

[Dave Ulrick]

I have two Intel NUC boxes that I use to run mythfrontend under Fedora 
34. I like to do most administration remotely using x11vnc. (That way I 
can use an ergonomic keyboard and sit in front of a monitor that's 
within good viewing distance...much more comfortable than using a 
wireless keyboard while trying to look at a distant TV.)

Sometimes remote control is nearly as fast as it would be to control the 
box locally--the OpenGL fade effects look pretty good and recording 
playback is very close to optimal--but other times it's extremely slow: 
 > 1 second delay for response to any keystroke. Once the slow behavior 
kicks in, it persists from one x11vnc session to another until 
mythfrontend is restarted or the box's monitor (TV) is turned on.

Note that the x11vnc slowness occurs even if I implement the solutions 
recommended for slowness issues: set -noxdamage, disable desktop 
compositing, disable vblank, etc..

Just now I figured out how this issue occurs:

1. The remote PC's monitor is turned off.
2. The screensaver on the remote PC has blanked the screen.
3. x11vnc is invoked.
4. The VNC viewer connects and shows a blank screen.
5. Pressing a key brings the screen to life but from then on 
mythfrontend is very slow via x11vnc.

My guess as to what's going on is that when the PC turns off the 
monitor, the X server loses sync so x11vnc falls back on a 
timeout-driven refresh scheme.

I have come up with a simple solution.

In my use case, I only have a monitor--that is, an HDTV switched to an 
HDMI input--turned on when I'm watching MythTV content. Otherwise, the 
monitor is turned off. Therefore, there's no need to run a screen saver. 
I didn't find a quick way to stop the screensaver (xfce4-screensaver) 
from running so I just went ahead and removed it from the boxes (dnf 
remove xfce4-screensaver).

Since removing the screensaver, the screen hasn't blanked so 
mythfrontend has retained fast performance over VNC.

Hope this helps someone out...

Dave