Rendering time is always different from time to time

I wonder why the rendering time to开发者_开发技巧 load a certain page is different from time to time (i used one certain browser). I have a java script code in that page..so when the page load, there will be a java script alert coming up.

I'm intending to compare the rendering time of a page in one browser to another. But, when only in one browser the rendering time could be different form time to time..how might i campare to another browser?? It's just hard to compare the rendering time of those browser.

Any idea why this could happen?

Thanks a bunch :)

Are you testing under lab conditions, ie. are you sure that there are no other burdens on your system resources when rendering the page.

Most importantly, are there any other processes running in your browser, extensions, other tabs etc. etc.

It's also very important where you're loading the page from, if it's not a local server then you have a lot of variables to consider.

Also, as nnnnnn points out, is it load time, or rendering time?

In short, the following factors can heavily influence render time:

• Caching rules
• Server speed & server load
• Cookies
• Network (your internet connection, the server's connection speed, etc.)

First, I'd check the caching rules. Depending on those, your browser might be told to only save static elements for a short amount of time, resulting in longer loading times when it is told to reload those.

Secondly, compare server speeds at different times of day (there's online tools for this). Also have a look on how 'busy' your server is. Especially shared servers can be quite slow from time to time.

Then, have a look at your code. If you're setting cookies, these might influence loading time depending on their size. The larger the cookies grow, the slower the site loading might become.