The recent rise of responsive design has highlighted the need for a refocusing on performance. Sites in general have definitely seen an increase in weight, but I don't think that Responsive sites are inherently heavier: at least, they don't have to be. Here are a couple of recent articles looking at performance as it relates to Responsive design.
- Responsive Design on a Budget on the Clearleft blog has an excellent idea: set a budget for page size. Doing so forces you to consider the cost / benefit of each addition and think about the relative importance of assets in/on the page.
- Brad Frost has a great article, Performance As Design, on his blog. In it, he suggests that performance should be considered as part of the design: good performance is good design.
- Tim Kadlec follows up with Setting a Performance Budget, and talks more about setting a performance budget.
This idea of more integrated areas, where each phase of development has little bits of everything, is becoming more widespread. Another good example is security: it should ideally be part of the project specification. Security should be built-in, not bolted on. I think this ties in well with the move to more iterative, short cycle, development processes.