Just a follow-up question to this topic:
I have too large views, one of them with 140 fields, of which perhaps only 40 are needed in the DataPage(s) that use these large views. I wonder if removing unnecessary fields will make a big difference and if it might be worth the effort. If the impact is marginal, I might not prioritize it right now. It is not unlikely that the huge amounts of lookup fields, drop downs, and, above all, formulas are what causes slow downloading/rendering. For every field the user fills, the entire form (or details page) starts re-loading all other fields (there are serial calculations in it).