Geek Answer

Facebook has a “ Lazy Loading ” system they call “ BigPipe ” that helps the pages load fast. Facebook breaks each page down into sections they call “ Pagelets” , and using Javascript only load the most important Pagelets first then load the less important ones shortly afterward. And pipeline them through several execution stages inside web servers and browsers, as the modern microprocessor do to serve the various request in an order to increase the productivity. Big Pipe is totally implemented in PHP and javascript. By loading and rendering the main page structure first with minimal info on it, the page appears to load quicker than having to wait for a complete page to download and then render. To exploit the parallelism between web server and browser, BigPipe first breaks web pages into multiple chunks called pagelets. Just as a  pipelining microprocessor  divides an instruction’s life cycle into multiple stages (such as “instruction fetch”, “instruction decode”, “executio