@superdan
I suggest following the RetroPie wiki instructions on 4K resolution performance issues: https://retropie.org.uk/docs/Pi4/?h=4k#4k-video-display

I was under the impression that tweakvc would work for RaspiOS Buster based systems, despite the comment on the project page.

Other option would be to add a correct sdtv_mode to config.txt - see here - but that would enable it permanently and wouldn't be a toggle as it is with tweakvc.

EDIT: it seems that the official firmware doesn't have PAL60 support, only some experimental versions which were beta tested as part of the Github topic mentioned above.

@henk Seeing as you CRT has Scart inputs it would be a downgrade to pair it with a Composite cable when the CRT has support for RGB. Look into PI2SCART or Recalbox RGB Dual instead and save yourself the hassle and trouble.

@mayfield

The problem is only affecting Mame so it must be a setting in mame

Launch a MAME game, press a button to open the launch menu and see if there's a custom video mode selected. If there is, clear it.

@tp3107 apologies, I have now fixed this through trial and error. Believe there was an override somewhere along the line.

@MCG_1983
Some shaders are effecting drastically performance. What shader are you using?

If you enable FPS counter, you will see the frames, so to be sure that you have frames drop and not screen tearing. You can enable this during the game from here :
Open Retroarch menu during game > Settings > On-Screen Display > On-Screen Notifications > Notification Visibility> Display Framerate

@mitu Thank you, youve made a grown man very happy

im not sure how this interacts with retroarch overrides as no video mode was selected in the override .cfgs the log file referenced but all i did was updated retroarch from binary to latest 1.16.0, loaded the same rom and i got a msg on lower left configuration override loaded but can change video mode from the runcommand launch menu and it now works.

i can now can select 50zh video mode and get smooth scrolling on PAL and on Amstrad CPC :)

@windg

That worked perfectly, thank you!

@retropieuser555 that's absolutely brilliant - thank you so much!

It appears that the original installation was done in Linux for some reason, so at least this way I can have a fiddle around and try to learn how it all works :)

Thanks once again - I'll get right on it.

@mitu
Thank you for your excellent support.
I was under the impression that both HDMI's mimic each other. It seems not to be the case.

I plugged the wire from one HDMI port to the other and it worked perfectly.
correction resolution and UI is 10 times faster along with the games and the input delay.

Thank you so much.

Please add some info about your setup, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first.

@DjDiabolik

You may also like this solution (autohiding the top-panel) :
https://fostips.com/auto-hide-top-panel-debian-ubuntu-fedora/
I used it for my VM.

Sadly, I run into a lot more issues with Ubuntu 22.04 :
my post about issues with Ubuntu 22.04

https://retropie.org.uk/docs/Shaders-and-Smoothing/

@mitu I've recompiled it with the SLD1 version and the speed is up again (hooray!) but it doesn't seem to want to output as opengl, so the screen size isn't playing ball again, sadly.

@mitu That's it! That was the solution.

Thanks for helping me out. I'd probably never had guessed that. Thanks a lot!

@dankcushions Thank you, I'll use that guide

Can you post your config.txt boot configuration ? What version of RetroPie are you using ?