Actually, I bet you don’t need to change color on all those rows. You only need to change ONE row back to white. You could set a variable to that row’s ID on the previous pass, and just change it.
I’m betting that’s going to be faster.
Here’s a demo project - waiting for 100 rows to clone is painfully slow (not related to my solution), but then the response to button pressing is fast.
If you’re checking performance on a slower device, wait until it finishes cloning first. It takes my 2016 iPhone /forever/ to finish.
I added timing for both approaches. If you click a label, it iterates through them. For 100 rows (slow iPhone/Live) with iterating (click the label), ~500ms. For 100 rows (same conditions but using list functions - click a button): ~20 ms. Your results will vary (your phone might be faster), but that’s a noticeable difference with 100 rows.
Got a list with 5 rows? Do whatever you want. It probably doesn’t matter much.
Setup to go fast:
I tested on web view also (fast computer). List functions ~1ms, iterate ~50ms.