地址：http://www.octagate.com/service/SiteTimer/

在URL of Site to Time后面的框中输如你要测试的网站就行了。

页面采用了Ajax，不用刷新页面，即能逐步的显示出测试结果。

官方说明：

About SiteTimer
Web Monitor allows you to monitor how long it takes for a user to download one or more of your web site pages.

It visits the page that your request and downloads all content that's directly linked from that page;

Images
Frames
IFrames
Script files
It follows redirects
As the pages are downloaded, SiteTimer stores statistics on how long time each item takes to download, and how much data they contained. This information is then presented in a grid.

Web Monitor correctly handles http compressed material (see OctaGate Switch), and it also honors keep-alive requests to give an accurate indication of the times a real browser would spend downloading the content.

Optimizing your site
Your page shouldn't take too long to load, slow load speeds will lead to users leaving your pages even though they're interested in the material. Users are becoming less and less accepting when it comes to slow sites as internet maturity increases.

The size of the page is the main deciding factor for download times, coupled with bandwidth. Though you can influence the bandwidth of your webservers, you cannot influence the bandwidth of your users. So make sure that your pages are no larger than they need to be. To reduce the size of your pages, you can;

Decrease the size of your images:

Use JPG instead of GIF or BMP. Sometimes PNG files are smaller than JPG files
Use harder compression on your jpg images
Make the images smaller in size
Reduce the number of images
Use HTTP compression on your web servers, which may compress code/text by up to 90%

If the first part of your page loads fast, and the parts that aren't visible yet take longer, than that's ok, because the users don't care about information that they're not ready to look at yet.

Reasons for slow load speeds
Pages can be slow to load for a number of reasons;

As mentioned above, the pages are simply too large
Your bandwidth is insufficient for the load that the users place on the page, in which case you'll need to upgrade your internet connection or migrate to a data center.
Your servers are overloaded and can't cope with the load that's placed on them, even though there's bandwidth to spare. In this case, you'll need to invest in more or better hardware. You may also want to look into load balancing.
Your users have low bandwidth - not all users have broadband, and even if they do, they may be located somewhere where internet connectivity is bad. Your only option here is to reduce the size of your page. Additionally, users may be on mobile devices such as cell phones, which have low bandwidth compared to broadband connections.


以下中文内容来自：http://www.itinit.com/read.php/176.htm
这个在线测速的站点不是你一般概念中的测速站点,主要针对于网站设计者开发,完整模拟了浏览器在对你的网页访问的时候整个页面的载入情况的时间表.
可以看到,不止抓取你的页面,就连你上面的各种js,css,以及各种图片等包括在你要测试的页面中的元素都能实时地演出抓取的开始和结束.演示页面采用了Ajax,使得结果非常直观和流畅地显示

提示,你不仅可以测试网站首页的载入情况,单个页面也是可以测试的,只要输入正确的网址就好了

当然,这个演示的时间表不尽科学,因为它是站在国外访问速度的角度来模拟的