> And my question still stands: who has numbers or data that show that those 14kb pages perform better in regard to the commercial metrics than heavier pages ? And I mean in the field data, not a synthetic test.

A trivial search will find you tons of heavily reviewed research that shows web page performance directly impacts e-commerce conversion/sales and this is widely known in the industry. This article laid out a solid technical explanation for why staying under 14kb can have substantial improvements in performance. You refusing to see the connection there, or are you disputing it?