I think i know what you mean. The lag you experience is due to “redrawing” the UI. When you change a label, that will often cause a slight delay as the screen is essential repainted on to the screen. At least, that’s how it works in my head. I expreience this consistnetly when changing labels. There is a very very slight lag depending on where the new label text is coming from. If it’s a cloud variable or firebase, this is slow. Up to .2 seconds. If it is a stored/app variable, it can be as fast as .1 second.
In my todo app, you will see that the app clones the rows way faster than it adds all the text to the labels in the rows.