If you use retroarch online updater to update cores you will get generic linux versions of them that are not optimized for RPi4... there is no repo for such update, thats why I included the core update in the addon settings, there you download the whole core pack from latest Lakka release for each device (RPi2, RPi4 and Generic).
Understood. Can´t thank you enough. Stay physically fit. (the usual word is censored)