I don't want to be rude, but I can't understand what you're asking. I have two possible answers, depending on how I have mis-understood your question.
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For years, web browsers have intentionally downloaded and displayed web pages and objects bit-by-bit, as each bit is downloaded. This prevents the user from staring at a blank page wondering if the web page is loading or not. The user sees progress, and the user gets the appearance of faster web browsing.
You want to undo this feature, and simply stare at a blank page until the entire web page has loaded, before anything gets displayed. I'm not even sure if a browser can do that anymore, but perhaps there is an option to be found. If so, I wouldn't know what it is, and I can't imagine a scenario where it would be useful.
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You want the browser to somehow expect that you are going to go to a particular web page, and it should pre-download all of the slower parts in advance before you decide to download the final "piece" that displays the web page.
I don't see how you can expect that to happen. The web browser can't know what to download until you tell it, and the web browser can't know what other pieces need to be downloaded until that web page tells it.
Some items can be cached locally, but if nothing else, the web browser needs to determine if the cache is still valid or out of date.