Size isn't everything! There is more to it than the Html document size. It is the total of all the objects on the page, each one represents an Http request (stylesheets, images, javascript, embedded objects, etc.) If any Http request is from an external server (ie: tracking code for site stats), then you are at the mercy of that server. If they are slow, you are slow. In the old days, they had what they called the unwritten "8 Second Rule" which was written for 56K modems. If the page did not load in that amount of time, then it was too large. Nowadays, however, anything over a few seconds is too long for most individuals. With broadband speeds at what they are, people no longer have to wait -- and this tends to make them more impatient. My rule of thumb is to keep your pages lean and mean. Optimize your images for the web, and do not stuff your pages with scores of them on the page. Keep your external Http requests to the bare minimum, throw out everything you can do without (this includes site counters, social media widgets, blog tracking code, etc.). If you are monetizing, ad servers can be a big drain on your page loading time. And if you cannot see all of the content (and properly rendered) above the fold within the first second and a half --- fix the problem.
Do you mean size of the files or size as in width of the page? If it is the latter you should be looking to use CSS to make it scalable if possible so it looks the same on most screen resolutions.
I guess a fluid layout would solve that problem. If it is a fixed width or you need to support browser screens for other types of equipment like PDAs or iPhones, then that is a whole different topic. On the matter of normal monitor widths, a majority is 1024 or larger. There is quite a few at 800, enough of them to cater to still.
That's why I am asking this question now - to have faster website loading time! So I need to understand what optimal webpage sizes it is desirable to have for a website in order it can be loaded as faster as it is possible!
If I have to set a fixed width vs fluid, I tend to head for "1024x768"; on my more popular sites it's far more common (and close to) and gives a little more working space than 800x600...
Actually, what is the normal webpage loading time? How long does it have to take for a webpage to be fully loaded? As far as I know Google took into account website loading time earlier? Is this time taken into account by Google now as well?
Since Google or any other SE only requests the Html page, then there is nothing else to hang it up. They do not download the images, external script files, frame content, embedded media, etc when they access that page. Any references to images, embedded objects, frames, etc will get queued at a separate time and by another bot.