Proper cookie usage

[pmeenan]

I'm not sure I would worry too much about it but if you need that last few milliseconds you need to split your dynamic (needs the cookies) content and static (css, js, images) into separate domains and make sure the "static domain" never has cookies set on it.

It's much easier to pull off if you are also using a CDN and need to split off your static resources anyway.

Since cookies are uploaded with every request (and the upstream bandwidth is usually slower for users) you can save some time by only having cookies sent when you really need them. That said, for most sites there is usually quite a bit of lower-hanging fruit to fix first and the ROI for the cookies may not be worth it.