1. A web server system, comprising: a plurality of physical servers that generate personalized web page content in response to page requests from users, wherein the physical servers generate the personalized web page content using user profile data associated with particular users; a level-of-service module that generates level-of-service parameters based at least in-part on current load levels of the plurality of physical servers; and a dynamic page generator that responds to the page requests according to the level-of-service parameters such that an amount of processing performed by the physical servers per page request in generating requested web pages decreases as said load level increases, and increases as said load level decreases, wherein the dynamic page generator controls said amount of processing performed by the physical servers at least partly by using the level-of-service parameters to vary a quantity of user profile data used by the physical servers to generate the personalized web page content; wherein the dynamic page generator is responsive to an increase in said load level by causing the physical servers to reduce, to a non-zero level, an amount of user profile data used to personalize web pages; whereby load levels are regulated in a feedback configuration.