Simulate that website is still loading, since it is fully loaded

I need some javascript or PHP code, that will simulate, that website is still loading in the browser, since it is fully loaded. Website is loading very fast, like 1-2 seconds, and I need it to load everything in 1-2 seconds AND still load for next 8 seconds.

I tried answer from here: Intentionally Slow Down HTML/PHP Page Load to Test

but ob_implicit_flush(true); and sleep(10); causes website to wait 10 sec and THEN it load all elements (it should load all elements and then sleep),

and Deelay.me act like img doesn't exist, without any delay.