Displaying "please wait"

Is there someone 'up' on the way Apache works who can offer some comment please? Th "how do I display 'please wait' " question was asked by someone (else) last week. The standard answer is "no" - server-side PHP assembles an HTML page, and when it is completed the whole page is transmitted from the web server to the browser. However is this strictly true? I managed to do something warned about in lesson two of ComSc 101, and put my PHP into a never-ending loop (hey, after all these years, it's just to keep me humble...). What was happening was that a database record would be read in, a whole pile of debug 'echo's sent to the screen to demonstrate the processing, then the next record, and so on... the governor/loop limit code failed and was stuck on 'true' so while true loop forever... What I saw on the screen - particularly the behavior of the scroll bars, was that a certain amount of data (let's call it a 'buffer') was produced within Apache, and then it would be sent to the screen, then there would be a short pause, then another 'buffer' load would be displayed in the browser, then a pause... This behavior similar to response from a long-distance www link or taking stuff down a slow dial-up line from an overloaded server; BUT everything on my machine is local ! Does this mean that Apache retains a certain amount of the page internally, but once the volume grows, Apache relieves storage pressure by transmitting even though the whole HTML page has not yet been resolved? If so, any idea what the 'buffer' size might be? Or is there any way to adjust that 'buffer' size HTML page by page? Enquiring minds and all that... =dn