I hate hearing these sorts of arguments when you have an inhouse business app served to a handful of repeat users. Reducing the payload size will make very little difference to most users as they visit the site every day and have most of it in cache. Also, speeding up the initial load times for internal users often does little to increase profits. Until it does it's hard to justify the work.
That said it's worth aiming to keeps things as small as possible from the start. Just not investing in a rewrite.
That said it's worth aiming to keeps things as small as possible from the start. Just not investing in a rewrite.