I just do not know why there would be a difference with respect to performance, or what NetSuite might be doing differently behind the scenes...

I would guess that in UI only 1 page of results is loaded and when you switch between pages they load additional data, so to actually test a difference in performance I would rather go for export all results to csv from UI and compare that to something simillar in script.

Have you tried the ‘n/query’ module? Maybe that performs better?

Are you loading the search in script or creating it from scratch in script?

that would make sense I suppose, it is only just doing the actual processing via pagination for that page at a time. and when you press the arrow to the next page it does look like it triggers an additional server call