[smp1]

Looks like there is a serious GUI performance bug that seem to be triggered by enabling/disabling Teletext.
I noticed that Kodi's sliding menus are sometimes not smooth, especially when watching a live TV and this can only be fixed by restarting Kodi/reboot.
I tried to find a way to reliably reproduce this issue and found out that the "jerkiness" appear when I enable and then disable teletext.

 @popcornmix 
This issue is still present. I also found out that this is triggered not only be enabling teletext. Running/exiting any game within Kodi (Retroplayer) will also make Estuary slower (this is very noticeable when using TV channel list). This is easy to reproduce just by running and exiting any game. After that the frame rate of the "sliding" Estuary menus is lower - the smoothness is gone. The setting "Limit GUI updates during playback" should be set to "Unlimited".

I think this is Pi-specific. I don't see this issue on a PC.