I don't think you can do it. But as for "slow" cookies - I think it's impossible. Cookies are not scripts or code etc. They are just little pieces of data (last visit date, your name etc). Cookie has very limited size so one cookie can't be greater than another etc. Every site is asking for it's own cookie, because it knows only those names of cookies it left in your browser. So I doubt that one or two very "special" cookies can slow down your browser