Need help optimizing page load time

trying to oprimize load time so that screen doesn't flicker

[Clay Wimberley]

Hello, this is my first post. I'm currently redesigning my company's web site and i'm focusing on it being very fast, easy to navigate and professional. My goal is to have the top and left navigation bars load practically instantaniously so that they have the same solid feel that you get from a framed site (a framed site where only the content of one frame changes so the navigation frames don't have to reload at all). It seems like if my navigation bars are set-up to load first, have very simple structure, a small file size, and don't change from page to page, they should load instantaniously. But, i've noiticed that many sites with this same basic structure still go blank and reload the nav. bars giving that "flickering" look when you load a new page. This flickering and flashing seems to be somewhat variable too. Sometimes the nav. bars flicker when I navigate say, from the "products" page the the "contact us" page, and sometimes (even performing the exact same navigation) the nav. bars will load instantly and perform just like a framed page. Also, i noticed that when i navigate using the "back" and "forward" button the pages load instantly. Does anyone have any insight they could give me? I'm not a web designer, but i'm really interested in learning about the finer points of optimizing my site.

[geoapa]

Don't use images for your navigation and ecspecially don't use images with javascript for an image-swapping roll-over affect (if any). The web pages will have to download (preload) the images each time a page is loaded.

I suggest using CSS along with SSI.

Just like the navigation system on this site, you can control font color, font size, font weight, background color, etc. with css.

I would also suggest puting your navigation menu system in a SSI file and calling it from your html pages. This way if you have to make a change to the navigation, you only make it once.

[WeirdoPL]

And also validate Your pages at:

[validator.w3.org...]

Many browsers will not go into "quirks" mode (or however it's spelled) and load Your pages generally faster than without validation (I think this doesn't concern IE though, but I'm not sure about it). :)

[vkaryl]

Also, i noticed that when i navigate using the "back" and "forward" button the pages load instantly.

This behavior is maybe most likely a function of the information already being cached by the time you begin navigation in this manner....

As to instantaneous loads: at work we have T-1s. Even with this setup which is MAGNITUDES faster than my 56k dial up at home, I have yet to visit an uncached/new site which loads instantaneously - and many of the sites I use at work are VERY well put together (I'm always looking at source on great sites, because if there's a better way out there to do something, I want to know it too....)

You might have to accept "not quite instantaneous".... or maybe one of the REALLY bright people around here has the answer!

[Farix]

As vkaryl has pointed out, there is no such thing as "instantaneous" on the Internet. Even when you load pages that are stored locally, there is always a slight delay as the browser clears the old page and loads the new page. You can minimize "the flicker" by keeping the page weight down, but you can never get rid of it. This is something you are going to have to live with.

[Rambo Tribble]

Andrew King's book, Speed Up Your Site: Web Site Optimizaton ISBN 0-7357-1324-3, is a good place to learn about page optimizaton.

[Clay Wimberley]

Thanks for all the good information. I Realize that the first time a page loads there is no way that it's going to come up instantly, but what i'm really wondering about is, once first page loads and the nav. bars are cached (assuming they are the exact same on each page)they could reload instantaneously when you navigate to a new page. I've seen this occur on many sites, but sometimes, even when the images are cahed, it flashes or flickers and sometimes it doesn't. Can anyone account for this variability (it's variable even when performing the exact same navigation steps). It's almost like the computer has more than one way of caching info. one type is quicker to retrieve for some reason. Or once the cache is full, it is slowed down somehow, or something like that.

[tedster]

It's more like a combination of the specific browser, its settings, and the headers from the server.

Sometimes, before re-using images from the browser cache, the browser checks with the server to see if the file has changed since it was cached before loading -- hence the visible pause.

[Clay Wimberley]

O.K. that makes sense. I have found one site that has a nav bar that absolutely doesn't flash or flicker. the wierd thing is that it's not a completely simple nav bar (drop down menues, and link text changes color after youv'e navigated to the appropriate page. It's not a framed page, but it is php (i'm assuming this since .php is at the end of the url)...maybe that makes a difference. I'm getting the sense that i'm not allowed to post the address of this site on this forum, but it there anyone who would be interested in me emailing them a link to this site so they can expalain to me how they think it's done? I would really appreciate it. Thanks to everyone for the good info so far.

[vkaryl]

You can sticky me with the addy and I'll take a look though there are bound to be others who post here who are way better at this sort of stuff than I am!