This is what I don't quite get; why make the distinction between "real speed" and "perceived speed"? Really, as far as the vast majority of your users are concerned, the speed of the page is from when they click you in a Google result to when Internet Explorer's status bar says "Done". How long your queries take relative to the page's rendering speed is irrelevant.

My main point is that the database and queries to it usually has much lower-hanging fruit for speed hacks.