My point is that both options could be same. I don't think that a display refresh rate can vary all the time, so "hdmiclocksync" probably means "sync playback to display", not vice versa.
If so, it could be a bug. Maybe the corresponding GUI setting has been overwritten by a wrong compiler flag. When "sync playback to display" is always active, it can result in frame drops.
PS: I have been informed the devs. Stay cool. 
hdmiclocksync is "Adjust display refresh rate to match video", not "sync playback to display".
Are you sure you have both options, not just "sync playback to display"?
2020-07-16 16:40:29.111 T:1390015360 DEBUG: COMXVideo::Open - decoder_component(0x0x5d414ba8), input_port(0x82), output_port(0x83) hdmiclocksync 1
vs.
Do not "sync playback to display" as that will force everything to be resampled and ARM devices are rubbish at that.
Yes, I know how de-interlacers work. It's not relevant to this discussion, and neither is overclocking as the issue is not related to CPU load.
Did you verified normal CPU load by using top or similar programs?
That is not correct at all, it de-interlaces it to 1080p50 depending on the de-interlacer setting. But there are a lot of different things going on when playing back such content, less video bandwidth for starters.
I'm at least partially correct. Here is the reference I mentioned: click.
As I said earlier, 1080i50 TV is fine for whatever reason.
If I remember right (I think chewitt explained it once - use the search function) 1080i reduces frame rate to half. There is no real interlaced mode on LE. You can try to overclock.
You best chance is to play with the A/V settings of the add-on. Read here about Netflix settings on RPi 3, just as an example for your preferred add-on. There is no universal solution for all add-ons.
If you decide to re-install LE from scratch, check your microSD first. Maybe bad blocks are the cause of the issue.
Is the screenshot from VNC or HDMI?
9.2.4 is the most recent LE version. You can copy it into the update folder, and reboot to install it.
To do so, you can login by SSH, and use wget to copy into the update folder. Or remove the microSD, and copy on your PC.
Hopefully the bug disappears after the update.
At which point you had the bug after vanilla LE installation?
Whats the add-on you try to display on the screen shot?
if that still doesn't work, the cable man should come again.
p.s. : he was there maybe 20 minutes, put his measuring device into the antenna socket and that's it ... a long-term test would be better.
Yep. 
The technician probably just measured constant date rate and check sums. The data rate of TV might suffer when EPG data (or other service) is updated. Then it would be a provider error. You should close out that case first, especially if the error happens at non-Kodi devices, too.
are you referring to the Settings -> System -> Peripherals?
Exactly, but because it's for CEC events, it can't help you for IR events.
Nicolas Maybe you're right, I'm not familiar with current DVB-C receiver cards. If the error happens at the same time on different devices, then it could be a provider error, too (worst case).
Not sure whether you got my point.
First, I don't think your cables (or even the fridge 
) are the problem. I know DVB-C cable problems, and they usually show up in missing or massively disturbed TV channels. That's not what you have.
My theory is that your DVB-C provider updates EPG data periodically, but (at least) your PC's DVB-C receiver is unable to process EPG data AND showing TV at the same time. Doing those two tasks at the same time probably needs more processing power than you currently have.
So my suggestion is to try a new DVB-C receiver card. It should have better processing power than your current one.
Nicolas I'm thinking of an EPG service, triggered at the same time:
I still want to get rid of one thing, today I ran my TV and the ASRock J5005-ITX with Digital Devices TV card at the same time, what can I say, the TV also had 4 BER errors at the same time.
