Hi,
With Resolve script API, coloring tons of items also takes a lot of time because of UI refreshing (you can see each items colored one by one, instead of the whole set of chosen items colored in one instant).
A PreventUIRefresh functions would be very much appreciated cause it could make such scripts way faster.
in REAPER script API you can do PreventUIRefresh(1) to stop refresh and -1 to restore it. Note that it also has some internal code so that if the script break or end for whatever reason without explicit RefreshUI reactivation, it does this on its on. We never know

Best,