JPG vs PNG (compression vs sprites) for page load times?

This question is in regards to another topic I was viewing elsewhere and I was really looking for some good input.

Page load times are critical now a days and people tend to use JPG for shopping cart sites when possible because of compression. In most cases JPG is better when there isnt a strict requirement for PNG, but if youre loading a lot of small PNG’s (icons, buttons, etc) wouldnt the advantage of using sprites outweigh the benefit of compression (if converted to JPG) when we talk about page load times?

I might save 50k off the page size but I go from 40 requests to 1.


CSS Sprites: Useful Technique, or Potential Nuisance?


The only problem with sprites I see is that there will be no gradual “pre-loading” that gives a customer a feeling of a more responsive website. With sprites the whole thing has to be downloaded to be then divided and parsed, and then displayed. If your server sets cache for images well enough, there should not be too much loading passed the initial page…